Wireless communication apparatus and method, and program

ABSTRACT

The present technology relates to a wireless communication apparatus and method, and a program which enable communication to be performed more efficiently. 
     The wireless communication apparatus includes a preamble generating unit configured to generate a preamble signal including header information, an inter-training generating unit configured to generate an inter-training signal including at least part of information of the header information, and a wireless transmission processing unit configured to transmit transmission data after transmitting the preamble signal in at least one or more frequency channels among a plurality of the frequency channels and transmit a plurality of the inter-training signals by utilizing one or a plurality of the frequency channels among the plurality of the frequency channels during a transmission period of the transmission data. The present technology can be applied to a wireless communication apparatus.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is based on PCT filing PCT/JP2018/034353, filedSep. 18, 2018, which claims priority to JP 2017-192382, filed Oct. 2,2017, the entire contents of each are incorporated herein by reference.

TECHNICAL FIELD

The present technology relates to a wireless communication apparatus andmethod, and a program, and, more particularly, to a wirelesscommunication apparatus and method, and a program which enablecommunication to be performed more efficiently.

BACKGROUND ART

In recent years, a high-density wireless local area network (LAN) systemhas been studied and developed, and a method has been devised, to whichan advanced spatial reuse technology which improves capacity of wirelessLAN terminals in related art and realizes high throughput is applied.

Particularly, as the advanced spatial reuse technology, a technology forallowing a signal of an own basic service set (BSS) and a signal from anoverlapping basic service set (OBSS) existing close to the own BSS tocoexist has been devised.

Specifically, for example, a communication method has been devised inwhich transmission of an own signal is performed within a range notaffecting the OBSS if received field strength (received power) of asignal from the OBSS close to the own BSS is equal to or lower thanpredetermined received field strength. Here, whether a signal is asignal from the own BSS or a signal from other OBSS is typicallyidentified on the basis of an identifier included in header informationadded to a head of a frame.

Further, in a cellular communication system in related art, existence ofdata transmitted using a data channel can be recognized by arranging acontrol channel and the data channel separately in advance and by aterminal decoding only control information transmitted using the controlchannel.

That is, for example, a technology of transmitting a signaling messageusing a shared signaling channel (see, for example, Patent Document 1)is proposed. In this technology, shared signaling channels are allocatedto subcarriers of the number determined in advance within an arbitraryframe, actual subcarriers periodically change, and signal power is madeto change on the basis of a baseband symbol.

CITATION LIST Patent Document

Patent Document 1: Japanese Patent Application Laid-Open No. 2013-153460

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

However, with the technology described above, it is difficult to performcommunication efficiently.

Specifically, in a case where an advanced spatial reuse technology isapplied, whether a received signal is a signal from a BSS or a signalfrom an OBSS is determined on the basis of header information added to ahead of a frame. Therefore, even if the received signal is a signal fromthe OBSS, if a head portion of the signal cannot be received, it hasbeen impossible to identify whether the received signal is a signal ofthe BSS or a signal from the OBSS. As a result, an apparatus is put intoa state where the apparatus cannot transmit an own signal, and itbecomes impossible to cause the advanced spatial reuse technology toeffectively function.

Further, even if some kind of signals is detected from a middle of aframe at a signal reception side, because information indicating aduration of the signal cannot be obtained, it has been impossible torecognize reception end time of the frame. Therefore, in order to startnew signal transmission after a frame which is being detected ends, itis necessary to always continuously detect a signal level.

Further, in a method in which a signaling message is transmitted using ashared signaling channel, it is necessary to recognize in advance whichsubcarrier is used for signaling. Therefore, such a method cannot beapplied to a system like a wireless LAN, in which signals areintermittently transmitted and received. That is, a communicationapparatus which operates as a base station has to always continuouslytransmit a signaling message using some kind of subcarriers.

The present technology has been made in view of such circumstances, andis directed to enabling communication to be performed more efficiently.

Solutions to Problems

According to the first aspect of the present technology, there isprovided a wireless communication apparatus including, a preamblegenerating unit configured to generate a preamble signal includingheader information; an inter-training generating unit configured togenerate an inter-training signal including at least part of informationof the header information, and a wireless transmission processing unitconfigured to transmit transmission data after transmitting the preamblesignal in at least one or more frequency channels among a plurality ofthe frequency channels and transmit a plurality of the inter-trainingsignals by utilizing one or a plurality of the frequency channels amongthe plurality of the frequency channels during a transmission period ofthe transmission data.

According to the first aspect of the present technology, there isprovided a wireless communication method or program including steps of:generating a preamble signal including header information; generating aninter-training signal including at least part of information of theheader information; and transmitting transmission data aftertransmitting the preamble signal in at least one or more frequencychannels among a plurality of the frequency channels and transmitting aplurality of the inter-training signals by utilizing one or a pluralityof the frequency channels among the plurality of the frequency channelsduring a transmission period of the transmission data.

In the first aspect of the present technology, a preamble signalincluding header information is generated, an inter-training signalincluding at least part of information of the header information isgenerated, and after transmitting the preamble signal in at least one ormore frequency channels among a plurality of the frequency channels,transmission data is transmitted, and a plurality of the inter-trainingsignals is transmitted by utilizing one or a plurality of the frequencychannels among the plurality of the frequency channels during atransmission period of the transmission data.

According to the second aspect of the present technology, there isprovided a wireless communication apparatus including: an inter-trainingdetecting unit configured to detect an inter-training signal includingat least part of information of header information included in apreamble signal from a received signal in one or a plurality offrequency channels among a plurality of the frequency channels; and awireless communication control unit configured to specify usagesituations of the plurality of the frequency channels on the basis ofthe detected inter-training signal.

According to the second aspect of the present technology, there isprovided a wireless communication method or program including steps of:detecting an inter-training signal including at least part ofinformation of header information included in a preamble signal from areceived signal in one or a plurality of frequency channels among aplurality of the frequency channels; and specifying usage situations ofthe plurality of the frequency channels on the basis of the detectedinter-training signal.

In the second aspect of the present technology, an inter-training signalincluding at least part of information of header information included ina preamble signal is detected from a received signal in one or aplurality of frequency channels among a plurality of the frequencychannels, and usage situations of the plurality of the frequencychannels is specified on the basis of the detected inter-trainingsignal.

Effects of the Invention

According to the first aspect and the second aspect of the presenttechnology, it is possible to perform communication more efficiently.

Note that the advantageous effects described here are not necessarilylimitative, and any of the advantageous effects described in the presentdisclosure may be attained.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a configuration example of a wirelessnetwork.

FIG. 2 is a diagram illustrating a configuration example of a frequencychannel.

FIG. 3 is a diagram illustrating a configuration example of a wirelesscommunication apparatus.

FIG. 4 is a diagram illustrating a configuration example of a wirelesscommunication module.

FIG. 5 is a diagram illustrating a typical frame format.

FIG. 6 is a diagram illustrating a configuration example of an L-SIG.

FIG. 7 is a diagram illustrating a configuration example of an HE-SIG-A.

FIG. 8 is a diagram illustrating a configuration example of atransmission frame subjected to frame aggregation.

FIG. 9 is a diagram illustrating a configuration example of a typicaltransmission frame in a case where an MPDU is transmitted by utilizing aplurality of frequency channels.

FIG. 10 is a diagram illustrating a configuration example of atransmission frame to which the present technology is applied.

FIG. 11 is a diagram illustrating a configuration example of atransmission frame to which the present technology is applied.

FIG. 12 is a diagram illustrating a configuration example ofinter-signal information.

FIG. 13 is a diagram explaining communication using typical advancedspatial reuse.

FIG. 14 is a flowchart explaining transmission processing.

FIG. 15 is a flowchart explaining reception processing.

FIG. 16 is a diagram illustrating a configuration example of a computer.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment to which the present technology is appliedwill be described with reference to the drawings.

First Embodiment

(Configuration Example of Wireless Network)

The present technology is a technology in which, in a case where aplurality of channels are aggregated (coupled) to be utilized as abroadband channel, part of preamble information and header informationwhich make a notification of attribute of frames transmitted in otherchannels is transmitted in a specific narrow band channel.

By this means, it is possible to cause peripheral wireless communicationapparatuses to recognize a usage situation of a wireless transmissionpath, so that it is possible to perform communication more efficiently.That is, the peripheral wireless communication apparatuses can recognizewhat kind of signal (frame) is transmitted in all channels by acquiringthis part of the preamble information and the header information.

Specifically, a specific frequency channel is set as a managementchannel, and, in a case where a wireless transmission path is utilized,part of header information is repeatedly transmitted following apredetermined preamble in the management channel. Transmission of partof the header information which is repeatedly performed is continuouslyperformed until a predetermined timing at which utilization of thewireless transmission path is finished.

In this case, for example, by setting a format of one of narrow bandchannels at a preamble format which utilizes a 20 MHz bandwidth inrelated art, also wireless communication apparatuses in related art canrecognize the usage situation of the wireless transmission path.Further, by attribute information, or the like, of the frame beingdescribed as preamble information to be transmitted by utilizing anarrow band channel (management channel), peripheral wirelesscommunication apparatuses can acquire information of the frametransmitted in a broadband channel.

Further, by shifting a frequency channel to be utilized as themanagement channel as necessary, it is also possible to allow a wirelesscommunication apparatus which performs communication by utilizing anarrow band channel to be notified of the usage situation of thewireless transmission path.

In this case, because a notification of part of the preamble informationand the header information is made by sequentially utilizing a pluralityof narrow band channels which constitutes a broadband channel as themanagement channel, it is possible to notify also a wirelesscommunication apparatus which utilizes only a narrow band channel of theusage situation of the wireless transmission path.

Further, in addition to part of the header information, arbitraryinformation may be added as information to be repeatedly transmitted inthe management channel.

For example, examples of the information to be transmitted in themanagement channel can include BSS Color information which isidentification information for identifying a BSS, information regardingtransmission power (transmitter power control (TPC)), informationregarding receiving sensitivity (DSC), information of a modulationscheme and a coding scheme of a data portion (modulation and codingscheme (MCS)), and parameters such as a remaining period of the frameand a data length (Length).

For example, by the BSS Color information being described as part of theheader information, in a case where a spatial multiplex reuse technologyis applied, each peripheral wireless communication apparatus canidentify whether a signal which is being transmitted is a signal from aBSS to which an own apparatus belongs or signals from other OBSSs.

Further, by describing information regarding transmission power of aframe to be transmitted and information regarding receiving sensitivityon a reception side in part of the header information, it is possible tonotify peripheral wireless communication apparatuses that transmissionpower control or receiving sensitivity control is performed.

A specific embodiment to which the present technology is applied will bedescribed below. FIG. 1 is a diagram illustrating a configurationexample of a wireless network including a wireless communicationapparatus to which the present technology is applied.

In the example illustrated in FIG. 1, relationship between the wirelesscommunication apparatus to which the present technology is applied andwireless communication apparatuses existing around the wirelesscommunication apparatus is illustrated.

That is, a wireless communication apparatus STA0 performs communicationby forming a wireless network with an access point AP1 of a first basicservice set to which the wireless communication apparatus STA0 belongs,that is, a BSS (hereinafter, referred to as a BSS1) and another wirelesscommunication apparatus STA1.

In other words, the wireless communication apparatus STA0, the accesspoint AP1, and the wireless communication apparatus STA1 belong to theBSS1 which is a wireless network, and these apparatuses constitute awireless communication system.

In this example, whether the detected signal is a signal transmittedfrom the apparatus which constitutes the BSS1 can be specified from theBSS Color information=0x01 indicating the BSS1, included in the signal.The BSS Color information is information for specifying a wirelessnetwork to which an apparatus of a transmission source of a signalincluding the BSS Color information belongs.

Further, around the wireless communication apparatus STA0, an accesspoint AP2 and a wireless communication apparatus STA2 of a second BSS(hereinafter, referred to as an OBSS2) which exists around the wirelesscommunication apparatus STA0 and which overlaps with the BSS1 alsoexist. Here, whether the detected signal is a signal transmitted from anapparatus which constitutes the OBSS2 can be specified from the BSSColor information=0x02 indicating the OBSS2, included in the signal.

Further, around the wireless communication apparatus STA0, an accesspoint AP3 and a wireless communication apparatus STA3 of a third BSS(hereinafter, referred to as an OBSS3) which exists around the wirelesscommunication apparatus STA0 and which overlaps with the BSS1 alsoexist. Here, whether the detected signal is a signal transmitted from anapparatus which constitutes the OBSS3 can be specified from the BSSColor information=0x03 indicating the OBSS3, included in the signal.

In this manner, in a case where the OBSS2 and the OBSS3 whosecommunication possible ranges overlap with a communication possiblerange of the BSS1 exist, for example, at the wireless communicationapparatus STA0, not only signals transmitted from the access point AP1and the wireless communication apparatus STA1 which constitute the BSS1,but also signals transmitted from apparatuses such as the access pointAP2, the wireless communication apparatus STA2, the access point AP3,and the wireless communication apparatus STA3 are also detected.

A configuration is employed where each BSS of the BSS1, the OBSS2, andthe OBSS3 performs transmission power control in accordance with asituation between wireless communication apparatuses which constitutethe BSS to perform communication.

For example, in the OBSS2 which is constituted with the access point AP2and the wireless communication apparatus STA2, and whose communicationsituation is more favorable than that of the BSS1, communication isperformed while transmission power is lowered. Further, in the OBSS3 inwhich the access point AP3 and the wireless communication apparatus STA3exist, and whose communication situation is poorer than that of theBSS1, communication is performed while transmission power is increased.

That is, each BSS employs a configuration where transmission powercontrol is performed in accordance with wireless communicationapparatuses which constitute the wireless network (BSS). Therefore,because communication is not performed at predetermined transmissionpower as in related art, and whether or not a transmission path can beutilized cannot be uniquely determined from received field strength(received power) of the received signal, it has been difficult toperform transmission control using carrier sense multipleaccess/collision avoidance (CSMA/CA).

Further, in recent years, it is studied to improve utilizationefficiency of a wireless transmission path by, for example, uponcommunication between the access point AP3 and the wirelesscommunication apparatus STA3 of the OBSS3, performing communicationwhile controlling transmission power from the wireless communicationapparatus STA0 to the access point AP1 so as not to affect thecommunication of the OBSS3.

That is, a configuration is employed where advanced spatial reuse isperformed by performing communication while communication within the ownBSS is made to overlap with communication of an irrelevant andoverlapping BSS (OBSS).

However, because communication between the access point AP2 and thewireless communication apparatus STA2 of the OBSS2, which is performedat transmission power smaller than transmission power of the own BSS islargely affected if communication from the wireless communicationapparatus STA0 to the access point AP1 is performed, it is necessary toperform control of refraining from transmission.

(Configuration Example of Frequency Channels)

Subsequently, a configuration of frequency channels allocated to thewireless communication system will be described. FIG. 2 is a diagramillustrating a configuration example of the frequency channels allocatedto the wireless communication system. Note that FIG. 2 illustrates afrequency on a horizontal axis.

For example, in an example indicated with an arrow Q11, in apredetermined frequency band, each frequency channel is set so thatbandwidths of all the frequency channels become 20 MHz in the frequencyband. That is, in this case, each frequency band whose bandwidth is 20MHz is utilized as the frequency channel, and a signal is transmittedfor each frequency channel.

In an example indicated with an arrow Q12, from the example indicatedwith the arrow Q11, further, two frequency channels whose bandwidths are20 MHz are bundled for some frequency channels adjacent to each other,and utilized as one frequency channel whose bandwidth is 40 MHz, thatis, as a broadband channel.

In this manner, by widening a bandwidth of the frequency channel, it ispossible to transmit more information efficiently. That is, for example,because utilization efficiency of a frequency band is higher in a casewhere a signal (frame) is transmitted using one frequency channel whosebandwidth is 40 MHz than in a case where the signal is transmitted usingtwo frequency channels whose bandwidths are 20 MHz, it is possible totransmit more information.

Moreover, because processing is performed for each frequency channelupon transmission and reception of a signal, as the number of frequencychannels is smaller, a processing amount upon transmission and uponreception becomes smaller, which results in shortening a processingperiod of processing required for transmission and reception.

In an example indicated with an arrow Q13, from the example indicatedwith the arrow Q12, further, two frequency channels whose bandwidths are40 MHz are bundled to be utilized as one frequency channel whosebandwidth is 80 MHz. That is, four frequency channels whose bandwidthsare 20 MHz are bundled to be utilized as one frequency channel whosebandwidth is 80 MHz (broadband channel).

Therefore, in this example, it is possible to utilize two frequencychannels whose bandwidths are 80 MHz and two frequency channels whosebandwidths are 20 MHz.

In an example indicated with an arrow Q14, from the example indicatedwith the arrow Q13, further, two frequency channels whose bandwidths are80 MHz are bundled to be utilized as one frequency channel whosebandwidth is 160 MHz. That is, eight frequency channels whose bandwidthsare 20 MHz are bundled to be utilized as one frequency channel whosebandwidth is 160 MHz. Therefore, in this example, it is possible toutilize one frequency channel whose bandwidth is 160 MHz and twofrequency channels whose bandwidths are 20 MHz.

Further, in an example indicated with an arrow Q15, from the exampleindicated with the arrow Q11, further, some frequency channels which areadjacent to each other are bundled and utilized as a mix of a pluralityof frequency channels whose bandwidths are different from each other.

That is, in this example, it is possible to utilize four frequencychannels whose bandwidths are 20 MHz, one frequency channel whosebandwidth is 40 MHz, and one frequency channel whose bandwidth is 80MHz.

In this manner, at the wireless communication apparatus, it is possibleto divide a predetermined frequency band into a plurality of bands withan arbitrary bandwidth and utilize each band as a frequency channel fortransmitting and receiving a signal.

(Configuration Example of Wireless Communication Apparatus)

A configuration of an apparatus which constitutes the BSS illustrated inFIG. 1 will be described next.

FIG. 3 is a diagram illustrating a configuration example of a wirelesscommunication apparatus to which the present technology is applied.

A wireless communication apparatus 11 illustrated in FIG. 3 correspondsto, for example, the wireless communication apparatus STA0, the wirelesscommunication apparatus STA1, or an apparatus such as the access pointAP1, which constitute the BSS1 illustrated in FIG. 1.

Note that, here, description will be provided assuming that the wirelesscommunication apparatus 11 is configured to be able to operate as eitheran access point such as the access point AP1 or a communication devicesuch as the wireless communication apparatus STA0, which constitute theBSS, that is, a wireless LAN system. However, the wireless communicationapparatus 11 may have a configuration in which a portion unnecessary foreach operation is omitted as appropriate.

The wireless communication apparatus 11 includes an internet connectionmodule 21, an information input module 22, an equipment control unit 23,an information output module 24, and a wireless communication module 25.

The internet connection module 21 functions as an adapter which isconnected to the Internet in a wired manner in a case where, forexample, the wireless communication apparatus 11 operates as the accesspoint. That is, the internet connection module 21 supplies data receivedvia the Internet to the equipment control unit 23 or transmits datasupplied from the equipment control unit 23 to a communication partnervia the Internet.

In a case where operation desired by a user is input by, for example, abutton, or the like, being operated by the user, the information inputmodule 22 acquires a signal in accordance with the operation of the userand supplies the signal to the equipment control unit 23. For example,in a case where various kinds of buttons and switches, a touch panel, amouse, a keyboard, or the like, is operated by the user, or in a casewhere the user performs input operation to a microphone, or the like,through speech, or the like, the information input module 22 determinesthe operation input and acquires a signal supplied in accordance withthe operation.

The equipment control unit 23 controls operation of the whole wirelesscommunication apparatus 11 in accordance with a signal, or the like,supplied from the information input module 22. That is, the equipmentcontrol unit 23 includes blocks, and the like, which realize functionscorresponding to a central processing unit (CPU) which manages controlof the operation of the wireless communication apparatus 11 in anintegrated manner and executes arithmetic processing, and an operatingsystem (OS).

For example, the equipment control unit 23 supplies predetermined datato the wireless communication module 25 and causes the data to betransmitted to a communication partner through wireless communication,or acquires data received from the communication partner from thewireless communication module 25. Further, the equipment control unit 23supplies information to the information output module 24 and causes theinformation to be displayed.

The information output module 24 includes, for example, a display, aspeaker, or the like, and outputs information supplied from theequipment control unit 23 to the user. For example, the informationoutput module 24 presents desired information to the user by causing theinformation supplied from the equipment control unit 23 to be displayedat a display of the own apparatus.

The wireless communication module 25 operates as a communication modulefor the wireless communication apparatus 11 to actually perform wirelesscommunication operation. That is, the wireless communication module 25transmits data supplied from the equipment control unit 23 in a frame ofa predetermined format through wireless communication, and receives asignal transmitted through wireless communication and supplies dataextracted from the received signal to the equipment control unit 23.

(Configuration Example of Wireless Communication Module)

Further, the wireless communication module 25 of the wirelesscommunication apparatus 11 is configured as illustrated in, for example,FIG. 4.

The wireless communication module 25 illustrated in FIG. 4 includes aninterface 51, a transmission buffer 52, a network managing unit 53, atransmission frame constructing unit 54, a wireless communicationcontrol unit 55, a header information generating unit 56, a preamblegenerating unit 57, an inter-training generating unit 58, a transmissionpower control unit 59, a wireless transmission processing unit 60, anantenna control unit 61, an antenna 62, a wireless reception processingunit 63, a detection threshold control unit 64, an inter-trainingdetecting unit 65, a preamble detecting unit 66, a header informationanalyzing unit 67, a received data constructing unit 68, and a receptionbuffer 69.

The interface 51 is connected to other modules which constitute thewireless communication apparatus 11 such as, for example, the equipmentcontrol unit 23, supplies data supplied from other modules to thetransmission buffer 52 and supplies data held at the reception buffer 69to other modules. Further, the interface 51 supplies informationsupplied from other modules such as the equipment control unit 23 to thenetwork managing unit 53 and supplies information supplied from thenetwork managing unit 53 to other modules such as the equipment controlunit 23.

The transmission buffer 52 holds data supplied from the interface 51 andsupplies the held data to the transmission frame constructing unit 54.

For example, the data held at the transmission buffer 52 is data storedin a media access control (MAC) layer protocol data unit (MAC protocoldata unit (MPDU)), to be transmitted in a wireless manner.

The network managing unit 53 manages a network which overlaps with theown network between the own apparatus and peripheral wirelesscommunication apparatuses. That is, the network managing unit 53supplies information supplied from the interface 51 and the receiveddata constructing unit 68 to the wireless communication control unit 55.Further, the network managing unit 53 instructs the transmission frameconstructing unit 54 to construct a frame including a predeterminednumber of MPDUs, or instructs the received data constructing unit 68 toconstruct data in a predetermined unit.

The transmission frame constructing unit 54 constructs a wirelesscommunication frame in a predetermined aggregation unit for wirelesscommunication by storing data held at the transmission buffer 52 in theMPDU in accordance with the instruction of the network managing unit 53or coupling a plurality of MPDUs.

The transmission frame constructing unit 54 supplies the constructedwireless communication frame to the wireless transmission processingunit 60 as a transmission frame and supplies necessary informationregarding the transmission frame to the header information generatingunit 56.

Note that, in the following description, the wireless communicationframe to be transmitted by the wireless communication apparatus 11 willbe also particularly referred to as a transmission frame, and datastored in the MPDU of the transmission frame will be also referred to astransmission data. Further, the wireless communication frame to bereceived by the wireless communication apparatus 11 will be alsoparticularly referred to as a received frame, and data stored in theMPDU of the received frame will be also referred to as received data.

The wireless communication control unit 55 performs access communicationcontrol on a wireless transmission path in accordance with predeterminedcommunication protocol.

That is, the wireless communication control unit 55 controls each unitof the wireless communication module 25 on the basis of information, orthe like, supplied from the network managing unit 53, the preambledetecting unit 66, the header information analyzing unit 67, or thelike, and controls transmission and reception through wirelesscommunication.

For example, the wireless communication control unit 55 suppliesnecessary information to the header information generating unit 56, thepreamble generating unit 57, the inter-training generating unit 58, thetransmission power control unit 59, the antenna control unit 61, and thedetection threshold control unit 64, and controls various kinds ofoperation regarding wireless communication and supplies informationregarding the network obtained from the received signal, or the like, tothe network managing unit 53.

The header information generating unit 56 generates various kinds ofinformation such as header information stored in a preamble, that is, apreamble signal on the basis of the information supplied from thetransmission frame constructing unit 54 and the wireless communicationcontrol unit 55, and supplies the information to the preamble generatingunit 57. That is, the header information generating unit 56 generatesoverhead information to be added to a head portion of the transmissionframe.

The preamble generating unit 57 generates a preamble on the basis of theinformation supplied from the header information generating unit 56 andthe wireless communication control unit 55, and supplies the preamble tothe wireless transmission processing unit 60 and supplies at least partof the information included in the preamble to the inter-traininggenerating unit 58. For example, the preamble is generated for each of aplurality of frequency channels.

The inter-training generating unit 58 generates an inter-training signalto be inserted into a middle of a signal of a frequency channel which isset as a management channel of the transmission frame on the basis ofthe information supplied from the preamble generating unit 57 and thewireless communication control unit 55 and supplies the inter-trainingsignal to the wireless transmission processing unit 60.

By this means, the inter-training signal is inserted into a middle ofthe signal of the management channel. In this inter-training signal,various kinds of parameters of a training sequence included in thepreamble, that is, information of a training field, the BSS Colorinformation, or the like, are included. Note that the management channelis a frequency channel in which transmission of the inter-trainingsignal is performed.

Further, the inter-training generating unit 58 supplies informationincluded in the generated inter-training signal to the transmissionpower control unit 59 as appropriate.

The transmission power control unit 59 adjusts (controls) transmissionpower of the transmission frame to be transmitted to other apparatuseswhich perform wireless communication with the wireless communicationapparatus 11 by controlling the wireless transmission processing unit 60and the antenna control unit 61 in accordance with an instruction fromthe wireless communication control unit 55. That is, the transmissionpower control unit 59 controls operation at the wireless transmissionprocessing unit 60 and the antenna control unit 61 so that thetransmission frame is transmitted at predetermined transmission power.

The wireless transmission processing unit 60 sets a final transmissionframe by adding the preamble supplied from the preamble generating unit57 for the transmission frame (MPDU) supplied from the transmissionframe constructing unit 54 and the inter-training signal supplied fromthe inter-training generating unit 58 to appropriate positions.

The wireless transmission processing unit 60 converts the obtainedtransmission frame into a predetermined baseband signal, performsmodulation processing and signal processing on the basis of the basebandsignal and supplies a transmission signal obtained as a result of theprocessing to the antenna control unit 61. That is, the wirelesstransmission processing unit 60 transmits a transmission signal(transmission frame) via the antenna control unit 61 and the antenna 62.

The antenna control unit 61 causes the transmission signal supplied fromthe wireless transmission processing unit 60 to be output (transmitted)from the antenna 62 in accordance with control by the transmission powercontrol unit 59. Further, the antenna control unit 61 supplies thereceived signal received by the antenna 62 to the wireless receptionprocessing unit 63.

The antenna 62 includes a plurality of elements, transmits thetransmission signal supplied from the antenna control unit 61 in awireless manner, receives the received signal which has beentransmitted, and supplies the received signal to the antenna controlunit 61.

The wireless reception processing unit 63 receives the received signalwhich is transmitted in a predetermined format in a wireless manner as areceived frame via the antenna 62 and the antenna control unit 61 bycomparing a detection threshold supplied from the detection thresholdcontrol unit 64 and received power of the received signal supplied fromthe antenna control unit 61. The wireless reception processing unit 63supplies the received frame to the inter-training detecting unit 65, thepreamble detecting unit 66, the header information analyzing unit 67,and the received data constructing unit 68.

The detection threshold control unit 64 determines the detectionthreshold to be used at the wireless reception processing unit 63 whileproviding and accepting necessary information to and from the wirelesscommunication control unit 55 and the transmission power control unit59, and supplies the detection threshold to the wireless receptionprocessing unit 63. This detection threshold is used to detect thepreamble and the inter-training signal included in the received signal.

The inter-training detecting unit 65 detects the inter-training signalinserted into a middle of a frame of the received signal (receivedframe) received at the wireless reception processing unit 63 for each ofa plurality of frequency channels, and supplies the detection result tothe header information analyzing unit 67.

The preamble detecting unit 66 detects the preamble added to the head ofthe received frame received at the wireless reception processing unit 63for each of a plurality of frequency channels and supplies the detectionresult to the wireless communication control unit 55 and the headerinformation analyzing unit 67.

The header information analyzing unit 67 extracts information such asthe overhead information of the received frame on the basis of thedetection results supplied from the inter-training detecting unit 65 andthe preamble detecting unit 66 and analyzes description content(description) of the information. Further, the header informationanalyzing unit 67 supplies the extracted information, that is,information read out from the preamble and the inter-training signal tothe wireless communication control unit 55 and the received dataconstructing unit 68.

The received data constructing unit 68 constructs the received signalreceived at the wireless reception processing unit 63, that is, dataincluded in the aggregated received frame as received data in apredetermined unit on the basis of the information supplied from theheader information analyzing unit 67. The received data constructingunit 68 supplies the constructed received data to the network managingunit 53 and the reception buffer 69.

The reception buffer 69 holds the received data supplied from thereceived data constructing unit 68 and supplies the held received datato the interface 51. The data held at the reception buffer 69 isreceived data extracted from a MAC layer protocol data unit (MPDU) ofthe received frame.

(Frame Format Example)

Here, a format of a signal provided and accepted between the respectivewireless communication apparatuses will be described.

For example, in a case where frame aggregation is not performed,typically, a transmission frame in a frame format illustrated in FIG. 5is transmitted and received between the wireless communicationapparatuses.

In the example illustrated in FIG. 5, a preamble is arranged at the headof data corresponding to one frame of the transmission frame, andtransmission data is arranged subsequent to the preamble.

That is, an L-STF, an L-LTF, an L-SIG, an RL-SIG, an HE-SIG-A, anHE-STF, and a predetermined number of HE-LTFs are sequentially arrangedin the preamble.

These L-STF, L-LTF, L-SIG, RL-SIG, HE-SIG-A, HE-STF, and HE-LTFs whichare overhead information are added to a head of the transmission frameas a predetermined preamble signal, and transmitted. Then, the receptionside recognizes that the transmission frame is transmitted by detectingexistence of the preamble.

The L-STF is called a short training field in related art (legacy shorttraining field), is utilized as a criterion for detection of start ofthe transmission frame and time synchronization processing, and is alsoutilized for estimation of a frequency error and automatic gain control(AGC). This L-STF has a configuration where a predetermined sequence isrepeated, and thus, the wireless communication apparatus on thereception side can detect a start position of the transmission frame bydetecting correlation of this sequence.

The L-LTF is called a long training field in related art (legacy longtraining field), and the L-LTF has a configuration where a predeterminedsequence is repeated. The L-LTF is utilized for performing channelestimation, estimation of a signal/noise (S/N), and time and frequencysynchronization.

The L-SIG is called a signal (legacy signal) field in related art, andis signaling information having a configuration where rate informationand length information of a data portion are described in an orthogonalfrequency division multiplexing (OFDM) symbol at a head.

The RL-SIG is information (signaling information) set for detecting thatthis transmission frame is not a frame using schemes of previousgenerations, but an HE-PPDU.

This RL-SIG and the L-SIG have completely the same information, and, inthe transmission frame, as a result of the L-SIG and the RL-SIG beingcontinuously arranged, the L-SIG is repeatedly arranged.

The wireless communication apparatus on the reception side can specifythat the transmission frame is a transmission frame in a format of apredetermined generation, that is, the transmission frame in a frameformat illustrating in FIG. 5 by detecting the L-SIG and the RL-SIGwhich are continuously arranged.

The HE-SIG-A is information (signaling information) in which informationfor enabling application of a spatial multiplexing technology is storedas an A filed of a signal in a high-density system.

While a configuration is employed where predetermined communication isperformed in accordance with parameters included in this HE-SIG-A, andparameters relating to the BSS Color information and Spatial Reuse aredescribed in the HE-SIG-A, various parameters are included other thanthese as necessary.

A portion formed with the L-SIG, the RL-SIG, and the HE-SIG-A in thepreamble is set as the header information.

Further, the HE-STF is a short training field (high efficiency shorttraining field) in a high-density system, and is utilized forsynchronization processing and adjustment of physical layer parameterswhich are required for realizing higher density.

The HE-LTF is a long training field (high efficiency long trainingfield) in a high-density system.

This HE-LTF has a configuration where trainings of the numbercorresponding to the number of spatial multiplexed streams are stored ina case where transmission is performed using spatial multiplexed streamsin multiple input multiple output (MIMO). That is, a predeterminednumber of the HE-LTFs are arranged after the HE-STF.

A portion from the L-STF to the HE-LTF described above is a preamblearranged at the head of the transmission frame. The wirelesscommunication apparatus on the reception side can recognize that thetransmission frame is transmitted by detecting such a preamble portion.

Further, Data subsequent to the preamble indicates transmission data,and a packet extention (PE) is arranged as necessary in a tail end ofthe transmission frame, subsequent to the transmission data.

Note that the long training field (LTF) such as the L-LTF and the HE-LTFmay be configured with a training sequence portion and a guard intervalportion. Further, the long training field may be configured such thatone guard interval is included in two OFDM symbols or may be configuredsuch that two guard intervals are included in two OFDM symbols.

Further, the L-SIG illustrated in FIG. 5 is configured as illustratedin, for example, FIG. 6.

In the example illustrated in FIG. 6, rate information indicated bycharacters “RATE”, length information indicated by characters “LENGTH”,a parity bit indicated by a character “P”, tail bit informationindicated by characters “Tail”, and the like, are included in the L-SIG.

The rate information is information indicating a rate (bit rate) oftransmission data indicated by characters “Data” illustrated in FIG. 5,and the length information is information indicating a length of thetransmission data indicated by the characters “Data” illustrated in FIG.5.

Further, the HE-SIG-A illustrated in FIG. 5 is configured as illustratedin, for example, FIG. 7.

In the example illustrated in FIG. 7, in the HE-SIG-A, as typicalparameters relating to the present technology, uplink/downlinkidentifier information indicated by characters “UL/DL”, MCS parameterinformation indicated by characters “MCS”, BSS Color informationindicated by characters “BSS Color”, parameter information regarding theadvanced spatial reuse technology indicated by characters “SpatialReuse”, transmission frame bandwidth information indicated by characters“Bandwidth”, parameter information of sizes of the guard interval andthe training field indicated by characters “GI+TF Size”, spatialmultiplexed stream number information indicated by characters “Nsts”,transmission opportunity duration information indicated by characters“TXOP Duration”, an error-detecting code (cyclic redundancy check (CRC))indicated by characters “CRC”, tail bit information indicated bycharacters “Tail”, and the like, are included.

For example, the MCS parameter is information indicating a modulationscheme and a coding scheme of the transmission data (transmissionframe), and the BSS Color information is information indicating a BSS(wireless network) to which an apparatus of a transmission source of thetransmission data belongs.

(Frame Configuration Example Upon Frame Aggregation)

Further, in a case where frame aggregation is performed, a frameconfiguration of a typical transmission frame is as illustrated in FIG.8.

FIG. 8 illustrates an example where four MAC layer protocol data units(MPDUs) are aggregated (coupled) as one transmission frame.

For example, in a case where each of the four MPDUs has a lengthdetermined in advance, that is, in a case where a length of the MPDU isa fixed length, the transmission frame is configured as indicated withan arrow Q31.

In this example, a preamble indicated by characters “Preamble” isarranged at the head of the transmission frame, and the aggregated MPDUsindicated by characters “MPDU-1” to “MPDU-4” are arranged after thepreamble.

In other words, the transmission frame has a configuration where apreamble is added to a head of a portion including a plurality of MPDUs.

This preamble includes a predetermined legacy training field, PHY headerinformation, and a training field for a predetermined spatialmultiplexed stream, and four MPDUs are synthesized with this preamble tomake one transmission frame.

In contrast, in a case where the length of the MPDU is a variablelength, the transmission frame is configured as indicated with an arrowQ32.

In this example, four MPDUs indicated by characters “MPDU-1” to “MPDU-4”are arranged subsequent to the preamble at the head of the aggregatedtransmission frame, and delimiter information indicated by a character“D” is arranged immediately before each of these MPDUs. Further, thepreamble in this example has the same configuration as the configurationin a case of the example indicated by the arrow Q31.

The delimiter information arranged immediately before each MPDU includesMPDU length information indicated by characters “MPDU Length”, and theCRC, and the MPDU length information indicates an information length,that is, a length of the MPDU arranged immediately after the delimiterinformation.

Further, in each MPDU, MAC header information indicated by characters“MAC Header” is arranged at a head portion of the MPDU. In this MACheader information, address information indicated by characters“Address”, and Duration information indicated by the characters“Duration” are stored.

Here, the address information is information indicating a destination ofthe MPDU, that is, an address identifying an apparatus of a transmissiondestination (recipient) of the transmission frame, and the Durationinformation is information indicating a duration of the MPDU. That is,because communication (transmission and reception) of the MPDU isperformed only for a duration indicated by this Duration information,the Duration information can be said as information indicating atransmission period of the MPDU.

In the MPDU, a payload indicated by characters “MAC Data Payload”, thatis, transmission data stored in the MPDU is arranged subsequent to theMAC header information. This payload has a variable length.

In the MPDU, a frame check sequence (FCS) indicated by characters “FCS”is arranged after the payload, that is, at a tail end of the MPDU. Withthis frame check sequence, the reception side of the transmission framecan perform error detection.

As described above, it is possible to make a transmission frame (burst)by bundling and aggregating a plurality of MPDUs in which transmissiondata having a variable length is stored and transmit the obtainedtransmission frame.

Further, in a wireless communication system, it is possible to divide apredetermined frequency band into a plurality of bands as describedabove, and transmit a transmission frame using these bands as onefrequency channel.

FIG. 9 is a diagram illustrating a configuration example of a typicaltransmission frame in a case where a plurality of MPDUs, that is, MPDUdata is transmitted by utilizing a plurality of frequency channels.

In the example illustrated in FIG. 9, some of the plurality of MPDUs(hereinafter, also simply referred to as MPDU-1 to MPDU-10) indicated bycharacters “MPDU-1” to “MPDU-10” are mapped on respective frequencychannels, and these MPDUs are aggregated and transmitted.

That is, in an example indicated with an arrow Q41, transmission data,that is, MPDU-1 to MPDU-7 are transmitted by utilizing four frequencychannels.

Specifically, MPDU-1 is transmitted over the entire duration of thetransmission frame by utilizing a first frequency channel. A portionformed with this MPDU-1 and a preamble indicated by characters“Preamble” becomes a signal of the first frequency channel in thetransmission frame.

Further, MPDU-2 is transmitted in a period slightly shorter than theduration of the transmission frame by utilizing a second frequencychannel. That is, in the second frequency channel, transmission ofMPDU-2 is performed during a period from transmission start time of thetransmission frame until time slightly earlier than time determined bythe duration of the transmission frame.

In a similar manner, MPDU-3 and MPDU-4 are transmitted in a periodslightly shorter than the duration of the transmission frame byutilizing a third frequency channel, and MPDU-5, MPDU-6, and MPDU-7 aretransmitted in a period slightly shorter than the duration of thetransmission frame by utilizing a fourth frequency channel.

Still further, as indicated with an arrow Q42, there can be a frameconfiguration where a plurality of frequency channels is aggregated(coupled), and transmission data is transmitted in frequency channelswith different bandwidths.

In an example indicated with the arrow Q42, the first and the secondfrequency channels in the example indicated with the arrow Q41 areaggregated, and set as a new broadband frequency channel.

For example, if original bandwidths of the first and the secondfrequency channels before aggregation are 20 MHz, a bandwidth of the newaggregated frequency channel formed with the first and the secondfrequency channels is 40 MHz, and bandwidths of the third and the fourthfrequency channels remain to be 20 MHz.

In this case, while the first and the second frequency channels areaggregated to be utilized as one frequency channel whose bandwidth is 40MHz, a preamble indicated by the characters “Preamble” is added to thetransmission frame for each frequency channel before aggregation.

In this example, in the aggregated frequency channel whose bandwidth is40 MHz, subsequent to the preamble, MPDU-1 to MPDU-4 are transmittedover the duration of the transmission frame.

Further, MPDU-5 to MPDU-7 are transmitted in a period slightly shorterthan the duration of the transmission frame by utilizing the thirdfrequency channel whose bandwidth is 20 MHz. Still further, MPDU-8 toMPDU-10 are transmitted in a period slightly shorter than the durationof the transmission frame by utilizing the fourth frequency channelwhose bandwidth is 20 MHz.

(Transmission Frame Configuration Example in the Present Technology)

By the way, as described above, in the transmission frame configurationillustrated in FIG. 9, the wireless communication apparatus whichreceives the transmission frame from a middle of the frame cannotrecognize a duration of the transmission frame and attribute of thetransmission frame, that is, whether the signal is a signal of the BSSor a signal of the OBSS, or the like.

Therefore, in the present technology, in a case where the transmissionframe is transmitted by utilizing a plurality of frequency channels, forexample, as illustrated in FIG. 10, the transmission frame configurationis employed in which the inter-training signal is repeatedly transmittedusing the management channel.

In the example illustrated in FIG. 10, the characters “Preamble”indicate a preamble, and, in this example, the MPDUs indicated by thecharacters “MPDU-1” and “MPDU-2” (hereinafter, also simply referred toas MPDU-1 and MPDU-2) are transmitted using four frequency channels.

That is, in this example, transmission data, that is, MPDU-1 istransmitted using the first and the second frequency channels, andMPDU-2 is transmitted using the fourth frequency channel. Here, thefirst and the second frequency channels are aggregated to make onebroadband frequency channel, and MPDU-1 is transmitted using thefrequency channel.

Note that destinations of MPDU-1 and MPDU-2, that is, wirelesscommunication apparatuses which become destinations of a signal(transmission frame) including MPDU-1 and a signal (transmission frame)including MPDU-2 may be the same or different from each other.

Further, in such a state, the inter-training signal indicated bycharacters “InterTF” is repeatedly transmitted over a duration of theMPDU using the third frequency channel.

Particularly, in this example, the third frequency channel is utilizedas the management channel, and this third frequency channel is a channelof a narrow band whose bandwidth is narrower than that of the broadbandchannel to be used for transmission of MPDU-1. Further, theinter-training signal is repeatedly transmitted at predetermined timeintervals in the third frequency channel.

Further, in the example illustrated in FIG. 10, a predetermined preamble(preamble signal) is added to a signal (transmission frame) to betransmitted in each frequency channel.

Here, in the preamble, to maintain compatibility with products inrelated art, the L-STF which is a legacy STF, the L-LTF which is alegacy LTF, the L-SIG which is a legacy SIGNAL, the RL-SIG which isrepetition of the L-SIG, the HE-SIG-A which is an A field of a signal ina high-density system, the HE-STF which is an STF in a high-densitysystem, and the HE-LTF which is an LTF in a high-density system aresequentially stored in line. Particularly, the HE-LTFs of the numbercorresponding to the number of signals to be synthesized in a spatialmultiplexing manner are added.

A portion including the L-SIG, the RL-SIG, and the HE-SIG-A among theoverhead information constituting the preamble is header information.

Further, as the inter-training signal, the L-STF, the L-LTF, the L-SIG,and the Inter SIG are sequentially arranged in line from the head. Thatis, a signal (information) including the L-STF, the L-LTF, the L-SIG,and the Inter-SIG is set as the inter-training signal.

Particularly, in this example, in the inter-training field(inter-training signal), to maintain compatibility with products inrelated art, a configuration is employed where the Inter-SIG which isinter-signal information is added to the L-STF which is a legacy STF,the L-LTF which is a legacy LTF, and the L-SIG which is a legacy SIGNAL.Here, the inter-signal information (Inter-SIG) is information includingat least part of information among the information included in theheader information. Further, the Inter-SIG may include information whichis not included in the header information.

The wireless communication apparatus 11 knows that the L-SIG is alwaysarranged after the L-STF and the L-LTF which are training signals, andthe RL-SIG and the HE-SIG-A or the inter-signal information is arrangedafter the L-SIG.

Therefore, the wireless communication apparatus 11 can detect thepreamble and the inter-training signal by detecting the L-STF and theL-LTF and can read out the header information, the inter-signalinformation, or the like, included in the preamble and theinter-training signal.

The transmission frame including one or a plurality of frequencychannels, transmitted by the wireless communication apparatus 11includes a preamble signal, transmission data (MPDU), and theinter-training signal. Further, in the inter-training signal, part ofthe header information, or the like, included in the preamble signal ofthe transmission frame is stored. Therefore, it can be said that theinter-training signal includes information regarding the transmissiondata within the same transmission frame.

Specifically, it is assumed, for example, that the inter-trainingsignal, MPDU-1, and MPDU-2 are transmitted by the same wirelesscommunication apparatus 11. In this event, for example, the L-SIG andthe inter-signal information of the inter-training signal includes rateinformation and length information of MPDU-1 and MPDU-2, parameters tobe applied to the spatial reuse technology, MCS parameters, a receivingsensitivity control level, or the like. That is, the L-SIG and theinter-signal information of the inter-training signal include part ofthe header information, or the like, within the preamble of thetransmission frame including MPDU-1 and MPDU-2.

In this example, one frequency channel is set as the management channel,and in the management channel, the inter-training signal isintermittently and repeatedly transmitted. Specifically, after oneinter-training signal is transmitted, after a section of no-signal, thatis, a section in which no signal is transmitted is provided for the sakeof expediency, the next inter-training signal is transmitted.

Among the wireless communication apparatuses, there is a wirelesscommunication apparatus which determines that a preamble and aninter-training signal are detected on the basis of change of a receivedsignal level when detecting the L-STF and the L-LTF after the section ofno-signal. Therefore, as in the example illustrated in FIG. 10, by asection of no-signal being provided between the inter-training signalsto be transmitted, such a wireless communication apparatus can alsocorrectly detect the preamble and the inter-training signal.

Note that, in the management channel, the inter-training signal may becontinuously transmitted without a section of no-signal being provided,or the inter-training signal may be transmitted at regular intervals orat irregular intervals by a section of no-signal being provided.

As described above, by the inter-training signal repeatedly includingpart of the header information being repeatedly transmitted in themanagement channel, that is, by the transmission frame continuouslyincluding a plurality of inter-training signals being transmitted, evena wireless communication apparatus which receives a middle of thetransmission frame can obtain part of the header information, or thelike.

By this means, because the wireless communication apparatus whichreceives the inter-training signal can recognize a usage situation ofthe wireless transmission path such as, for example, the duration of thetransmission frame and attribute of the transmission frame, it ispossible to perform communication more efficiently.

Further, in FIG. 10, an example has been described where aggregation isperformed over four frequency channels, that is, an example where fourfrequency channels are utilized. However, there may be any number offrequency channels, and a plurality of arbitrary frequency channels maybe aggregated to be utilized as one frequency channel. In this event, abandwidth of the management channel is preferably equal to or narrowerthan bandwidths of frequency channels in which other transmission data(MPDU) is to be transmitted.

Further, for example, as illustrated in FIG. 11, a frequency channel tobe utilized as the management channel may be shifted (changed) overtime.

Note that, in FIG. 11, the characters “Preamble” indicate the preamble,and characters “MPDU-1” to “MPDU-12” indicate the MPDUs. Further,characters “InterTF” indicate the inter-training signal. In thefollowing description, the MPDUs indicated by the respective characters“MPDU-1” to “MPDU-12” will be also simply referred to as MPDU-1 toMPDU-12.

In the example illustrated in FIG. 11, the transmission frame includingthe MPDUs and the inter-training signal is transmitted using fourfrequency channels.

Specifically, in an example indicated with an arrow Q51, MPDU-1 istransmitted using a first frequency channel, and MPDU-4 is transmittedusing a fourth frequency channel. Particularly, MPDU-1 is transmittedover the entire duration of the transmission frame in the firstfrequency channel.

Further, in such a state, in the second frequency channel, MPDU-2 istransmitted in a first half of the transmission frame, and theinter-training signal is intermittently and repeatedly transmitted in alast half of the transmission frame.

Still further, in the third frequency channel, the inter-training signalis intermittently and repeatedly transmitted in the first half of thetransmission frame, and MPDU-3 is transmitted in the last half of thetransmission frame.

Therefore, in this example, the third frequency channel is set as themanagement channel in the first half of the transmission frame, and theinter-training signal is repeatedly transmitted in the third frequencychannel. In this event, in the second frequency channel which is not setas the management channel, MPDU-2 which is transmission data istransmitted.

Further, in the last half of the transmission frame, the managementchannel is switched (shifted) from the third frequency channel to thesecond frequency channel, and the inter-training signal is repeatedlytransmitted in the second frequency channel. In this event, in the thirdfrequency channel which is no longer the management channel, MPDU-3 istransmitted.

In a case where the frequency channel which is set as the managementchannel is shifted over time, the frequency channel which is set as themanagement channel at a certain timing has a section in which theinter-training signal is transmitted and a section in which the MPDU istransmitted. That is, the inter-training signal is transmitted at atiming before transmission or after transmission of the MPDU.

In this manner, by shifting the frequency channel (frequency band) whichis set as the management channel, it is possible to notify more wirelesscommunication apparatuses of a usage situation of the wirelesstransmission path.

It is, for example, assumed that there is a wireless communicationapparatus which cannot receive a signal in the third frequency channelbut can receive a signal in the second frequency channel.

In this case, such a wireless communication apparatus cannot receive theinter-training signal included in the third frequency channel which isset as the management channel in the first half of the transmissionframe. However, at a timing at which the last half of the transmissionframe is transmitted, because the wireless communication apparatus canreceive a signal in the second frequency channel which is set as themanagement channel, that is, the inter-training signal, the wirelesscommunication apparatus can recognize the usage situation of thewireless transmission path.

Further, in an example indicated with an arrow Q52, all the frequencychannels in which the MPDU which is data is transmitted are utilized asthe management channel, and the inter-training signal is distributed ina time direction and transmitted using these frequency channels.

That is, in this example, it is assumed that four frequency channels aresequentially utilized as the management channel.

Specifically, at a first timing, the third frequency channel is set asthe management channel, and the inter-training signal is transmitted inthe third frequency channel, and, at the next timing, the inter-trainingsignal is transmitted in the second frequency channel.

Further, at the subsequent timing, the inter-training signal istransmitted in the first frequency channel, and, at the last timing, theinter-training signal is transmitted in the fourth frequency channel.

Therefore, in the first frequency channel, MPDU-1 is transmittedimmediately after transmission of the transmission frame is started,and, thereafter, when the first frequency channel becomes the managementchannel, the inter-training signal is repeatedly transmitted, andfurther thereafter, when the first frequency channel is no longer themanagement channel, MPDU-5 is transmitted.

Further, in the second frequency channel, after MPDU-2 is transmitted,the second frequency channel is set as the management channel, and theinter-training signal is repeatedly transmitted, and thereafter, whenthe second frequency channel is no longer the management channel, MPDU-6is transmitted. In the third frequency channel, the third frequencychannel is set as the management channel immediately after transmissionof the transmission frame is started, and the inter-training signal istransmitted, and thereafter, when the third frequency channel is nolonger the management channel, MPDU-3 is transmitted.

Still further, in the fourth frequency channel, when MPDU-4 and MPDU-7are sequentially transmitted, thereafter, the fourth frequency channelis set as the management channel, and the inter-training signal isrepeatedly transmitted until a timing of completion of transmission ofthe transmission frame.

That is, in this example, from a timing of the head of the transmissionframe until a timing of completion of transmission of the transmissionframe, the respective frequency channels of the third frequency channel,the second frequency channel, the first frequency channel, and thefourth frequency channel are sequentially utilized as the managementchannel. Then, the inter-training signal is transmitted in thesemanagement channels.

Further, in an example indicated with an arrow Q53, while a plurality offrequency channels is utilized as the management channel, the MPDU isconfigured by utilizing a plurality of frequency channels in somesections. That is, a plurality of frequency channels is bundled andutilized as a broadband frequency channel. Further, the inter-trainingsignal is transmitted in individual frequency channels between the MPDUsin the plurality of frequency channels.

Specifically, in this example, subsequent to a predetermined preamble,MPDU-1 is transmitted by utilizing four frequency channels of the firstto the fourth frequency channels which are aggregated to be utilized asone broadband frequency channel. That is, MPDU-1 is transmitted usingthe first to the fourth frequency channels.

When MPDU-1 is transmitted, in a state where MPDU-2 is being transmittedusing the second to the fourth frequency channels, the first frequencychannel is utilized as the management channel, and the inter-trainingsignal is repeatedly transmitted in the first frequency channel.

Further, thereafter, MPDU-5 is transmitted using the first frequencychannel, MPDU-3 is transmitted using the third and the fourth frequencychannels, and the inter-training signal is repeatedly transmitted usingthe second frequency channel as the management channel.

Further, at a timing at which transmission of MPDU-3 is completed,MPDU-5 is continuously transmitted in the first frequency channel, and,when transmission of MPDU-5 is completed, thereafter, MPDU-7 istransmitted in the first frequency channel.

Further, at a timing at which transmission of MPDU-3 is completed,MPDU-6 is transmitted in the second frequency channel, MPDU-4 istransmitted in the fourth frequency channel, and the inter-trainingsignal is repeatedly transmitted using the third frequency channel asthe management channel. Note that it is also possible to prevent theinter-training signal from being transmitted in some sections such as asection in a tail end portion of the transmission frame.

Also in the example indicated with the arrow Q53, the management channelis shifted sequentially from the first frequency channel to the secondfrequency channel and, then, the third frequency channel.

Further, as indicated with an arrow Q54, a plurality of sections of thetransmission frame, which is different from each other may be utilizedas the management channel in one frequency channel.

In this example, subsequent to the preamble, respective MPDU-1 to MPDU-4are transmitted respectively in the first to the fourth frequencychannels.

Further, when transmission of MPDU-1 is completed, the first frequencychannel is set as the management channel, and the inter-training signalis transmitted in the first frequency channel.

Then, because transmission of MPDU-2 is completed at a timing at whichtransmission of this inter-training signal is completed, the secondfrequency channel is set as the management channel, and theinter-training signal is transmitted in the second frequency channel. Inthis event, transmission of MPDU-5 is started in the first frequencychannel.

In addition, because transmission of MPDU-3 is completed at a timing atwhich transmission of the inter-training signal in the second frequencychannel is completed, the third frequency channel is set as themanagement channel, and the inter-training signal is transmitted in thethird frequency channel. In this event, transmission of MPDU-6 isstarted in the second frequency channel.

Further, because transmission of MPDU-5 is completed at a timing atwhich transmission of the inter-training signal in the third frequencychannel is completed, the first frequency channel is set as themanagement channel, and the inter-training signal is transmitted in thefirst frequency channel. In this event, transmission of MPDU-7 isstarted in the third frequency channel, and, when transmission of MPDU-4is completed during transmission of the inter-training signal in thefirst frequency channel, transmission of MPDU-8 is started in the fourthfrequency channel.

Because transmission of MPDU-6 is completed at the time whentransmission of the inter-training signal in the first frequency channelis completed, the second frequency channel is set as the managementchannel, and the inter-training signal is transmitted in the secondfrequency channel. In this event, transmission of MPDU-9 is started inthe first frequency channel.

Further, because transmission of MPDU-7 is completed at a timing atwhich transmission of the inter-training signal in the second frequencychannel is completed, the third frequency channel is set as themanagement channel, and the inter-training signal is transmitted in thethird frequency channel. In this event, transmission of MPDU-10 isstarted in the second frequency channel.

Further, when transmission of MPDU-8 is completed in the fourthfrequency channel, transmission of MPDU-12 is started subsequent to thetransmission of MPDU-8, and, when transmission of the inter-trainingsignal in the third frequency channel is completed, MPDU-11 istransmitted in the third frequency channel thereafter.

In this example, for the entire frequency band, the first to the thirdfrequency channels are sequentially and repeatedly set as the managementchannel. That is, when the third frequency channel is set as themanagement channel, the first frequency channel is set as the managementchannel again thereafter.

Further, when, for example, attention is focused on the first frequencychannel, a state where the first frequency channel is the managementchannel and a state where the first frequency channel is not themanagement channel are alternately repeated, such that the firstfrequency channel is set as the management channel after MPDU-1 istransmitted, and further, thereafter, the first frequency channel is nolonger the management channel again, and MPDU-5 is transmitted. That is,the inter-training signal is transmitted in the first frequency channelat a timing before transmission data (MPDU) is transmitted and at atiming after the transmission data is transmitted.

As described above, there are various kinds of variation in atransmission method of the inter-training signal, that is, a selectionmethod of the management channel. Any transmission pattern of theinter-training signal may be employed if a plurality of inter-trainingsignals is transmitted at regular intervals or irregular intervals whenviewed in a time direction.

That is, a plurality of inter-training signals is transmitted at regularintervals or at irregular intervals when viewed in a time direction,and, at each timing at which the inter-training signal is transmitted,it is only necessary that the inter-training signal is transmitted usingat least one frequency channel among one or a plurality of frequencychannels.

For example, when attention is focused on one wireless communicationapparatus 11, at the wireless communication apparatus 11, the MPDU inwhich transmission data is stored is transmitted after the preamblesignal is transmitted in at least one or more frequency channels among aplurality of frequency channels. Further, at the wireless communicationapparatus 11, during transmission of the transmission data, that is,during a transmission period, one or a plurality of frequency channelsamong the above-described plurality of frequency channels is set as themanagement channel, and a plurality of inter-training signals istransmitted by utilizing the management channel after transmission ofthe preamble signal.

Note that, because the inter-training signal is repeatedly transmitted,a bandwidth of the management channel to be used for transmission of theinter-training signal may be equal to or less than the bandwidth of thefrequency channel in which MPDU which is transmission data istransmitted.

(Configuration Example of Inter-Signal Information)

A configuration example of inter-signal information (Inter-SIG)constituting the inter-training signal, to which the present technologyis applied, will be described next.

For example, the inter-signal information is configured as illustratedin FIG. 12.

In the example illustrated in FIG. 12, the inter-signal informationincludes a portion configured with the same signal as a signal of thesignal information (L-SIG) in related art indicated with an arrow Q61, aportion of Inter-SIG 1 indicated with an arrow Q62, and a portion ofInter-SIG 2 indicated with an arrow Q63. Note that the configuration ofthe inter-signal information is not limited to the configurationillustrated in FIG. 12, and may be any configuration.

A portion of the signal information (L-SIG) indicated with the arrow Q61may have the same configuration as bit arrangement in, for example, thelegacy L-SIG in related art. Here, bit arrangement of the portion of thesignal information indicated with the arrow Q61 is the same as the bitarrangement of the legacy L-SIG.

That is, a portion of the signal information (L-SIG) indicated with thearrow Q61 includes rate information (Rate) indicating a rate of thetransmission data, Reserved (R) which is a Reserved region, lengthinformation (Length) indicating Remaining Duration which is a remainingperiod of this transmission frame, and information such as parity (P).

Particularly, the length information is information regarding atransmission period of the transmission data, that is, a transmissionperiod of a transmission frame including transmission data and theinter-training signal to be transmitted by one wireless communicationapparatus. Therefore, it is possible to set network allocation vector(NAV) information which is a period during which transmission of an ownsignal is inhibited on the basis of this length information.

Further, a portion of Inter-SIG 1 indicated with the arrow Q62 includeschannel map information indicated by characters “Using Frequency ChannelMap”, BSS Color information indicated by characters “BSS Color”, atransmission power control level indicated by characters “TPC Level”,parameters to be applied to a spatial reuse technology indicated bycharacters “Spatial Reuse”, and information indicating a modulationscheme and a coding scheme of the transmission frame (coding andmodulation scheme information), indicated by characters “MCS”.

The channel map information is information regarding a frequency channelto be utilized for transmission of the transmission data (MPDU). Morespecifically, the channel map information is information indicatingmapping of frequency channels to be utilized for a series of datatransmission, that is, information indicating a usage situation of thewireless transmission path such as information indicating what kind offrequency channels exist and what kind of transmission data istransmitted in each frequency channel. Therefore, by referring to thischannel map information, each wireless communication apparatus canrecognize the usage situation of the wireless transmission path(frequency band) such as what kind of frequency channels exist andwhether transmission data is transmitted in each frequency channel.

Further, the BSS Color information is information for identifying a BSSto which an apparatus which transmits the inter-training signalincluding this inter-signal information, that is, an apparatus of atransmission source of the signal belongs, and the transmission powercontrol level (TPC Level) is transmission power information indicatingtransmission power of the transmission frame.

Note that, among the portion of the Inter-SIG 1 indicated with the arrowQ62, for example, the BSS Color information and parameters (SpatialReuse) to be applied to the spatial reuse technology, information (MCS)indicating a modulation scheme and the coding scheme, and the like, areheader information of the preamble, more particularly, informationincluded in the HE-SIG-A.

Further, a portion of the Inter-SIG 2 indicated with the arrow Q63includes a receiving sensitivity control level (DSC Level) which isreceiving sensitivity information indicating receiving sensitivity ofthe transmission frame, information of part of an address indicating awireless communication apparatus which is a transmission source or arecipient of the transmission frame (AID12), an error detection code(CRC) of the inter-signal information, a Tail bit indicating an end, andthe like.

Note that information (parameters) described in the inter-signalinformation is not limited to the information illustrated in FIG. 12,and may be any other information. That is, further other information maybe added to the information illustrated in FIG. 12, or part of theinformation may be deleted from the information illustrated in FIG. 12.Specifically, in addition to the information illustrated in, forexample, FIG. 12, further, an identifier indicating a frame type (type)of the transmission frame such as a management frame for controlling aframe, or the like, in which the inter-training signal is transmittedand an action frame for exchanging parameters may be included in theinter-signal information.

(Improvement of Communication Efficiency by the Present Technology)

By the way, in a case where transmission of the inter-training signal isnot performed as in the present technology, if a portion of the headerinformation of the transmission frame cannot be correctly received,transmission efficiency degrades due to retransmission of thetransmission frame.

Specifically, it is assumed, for example, that the access point AP1illustrated in FIG. 1 transmits a transmission frame to the wirelesscommunication apparatus STA0, and the access point AP2 illustrated inFIG. 1 transmits the transmission frame to the wireless communicationapparatus STA2 at the same time.

Here, the transmission frames to be transmitted by the access point AP1and the access point AP2 are frames having a typical configuration intowhich the inter-training signal is not inserted.

In such a case, for example, as illustrated in FIG. 13, if the headerinformation of the transmission frame cannot be correctly received,transmission efficiency (communication efficiency) degrades due toretransmission of the transmission frame.

In the example illustrated in FIG. 13, in the middle of transmission ofa transmission frame FL31 addressed to the wireless communicationapparatus STA0 by the access point AP1 of the own BSS1, the access pointAP2 of the OBSS2 transmits a transmission frame FL32 addressed to thewireless communication apparatus STA2.

Here, because the wireless communication apparatus STA0 can correctlyreceive the transmission frame FL31, the wireless communicationapparatus STA0 transmits an ACK frame FL33 indicating that thetransmission frame FL31 can be received, to the access point AP1.

However, interference (collision) occurs by this ACK frame FL33, and thewireless communication apparatus STA2 cannot correctly receive thetransmission frame FL32, which results in a state where a communicationerror occurs. The wireless communication apparatus STA2 transmits an ACKframe FL34 indicating only the MPDU of the transmission frame FL32,which can be correctly received, to the access point AP2.

Further, while a transmission frame FL35 addressed to the wirelesscommunication apparatus STA0 is transmitted from the access point AP1 ata transmission timing of the ACK frame FL34, a communication erroroccurs at the wireless communication apparatus STA0 due to interferenceof this transmission frame FL35 and the ACK frame FL34. That is, at thewireless communication apparatus STA0, the transmission frame FL35cannot be correctly received. The wireless communication apparatus STA0transmits the ACK frame FL36 indicating only the MPDU of thetransmission frame FL35, which can be correctly received, to the accesspoint AP1.

Further, while the access point AP2 retransmits a transmission frameFL37 corresponding to the MPDU of the transmission frame FL32, whichcannot be correctly received, in response to the ACK frame FL34, acommunication error occurs at the wireless communication apparatus STA2due to interference of this transmission frame FL37 and the ACK frameFL36. That is, at the wireless communication apparatus STA2, thetransmission frame FL37 cannot be correctly received.

In this manner, in the example illustrated in FIG. 13, in the middle ofcommunication from the access point AP1 of the BSS1 to the wirelesscommunication apparatus STA0, communication from the access point AP2 ofthe nearby OBSS2 to the wireless communication apparatus STA2 is alsoperformed. Further, while communication errors occur by each other's ACKframes of the communication, because transmission power control is notperformed upon retransmission of the transmission frame thereafter,collision of signals repeatedly occurs, which degrades communicationefficiency.

In a transmission frame having a typical configuration, the BSS Colorinformation for identifying the BSS, a transmission power control level(TPC Level), and parameters (Spatial Reuse) to be applied to theadvanced spatial reuse technology cannot be obtained in the middle ofthe transmission frame. Therefore, in a case where collision of signalsoccurs, upon retransmission and upon return of the ACK frame,transmission power control cannot be performed, and there is a casewhere collision of signals repeatedly occurs.

In contrast, it is assumed, for example, that the access point AP1illustrated in FIG. 1 transmits a transmission frame to the wirelesscommunication apparatus STA0, and the access point AP2 illustrated inFIG. 1 transmits the transmission frame to the wireless communicationapparatus STA2 at the same time.

In such a case, in the present technology, the inter-training signalillustrated in FIG. 10 and FIG. 11 is included in at least one ofsignals of the respective frequency channels of the transmission frame.In such a state, by performing transmission power control of thetransmission frame using information obtained from the inter-trainingsignal and transmitting signals (transmission frame) using advancedspatial reuse, it is possible to suppress occurrence of collision ofsignals, so that it is possible to perform communication moreefficiently.

(Explanation of Transmission Processing)

Subsequently, operation of the wireless communication apparatus 11 willbe described.

First, transmission processing to be performed when the wirelesscommunication apparatus 11 transmits a transmission frame will bedescribed. That is, transmission processing by the wirelesscommunication apparatus 11 will be described below with reference to theflowchart in FIG. 14.

In step S11, the interface 51 receives supply of transmission data fromthe equipment control unit 23.

For example, in a case where the wireless communication apparatus 11transmits transmission data to other wireless communication apparatuses,transmission data input by an application program, or the like, issupplied from the equipment control unit 23 to the transmission buffer52 via the interface 51 of the wireless communication module 25.

In step S12, the network managing unit 53 acquires information regardingthe wireless communication apparatus on a reception side.

For example, in a case where the transmission data is supplied to thetransmission buffer 52, at the same time, destination informationindicating a destination of the transmission data, communication partnerinformation regarding a communication partner of the wirelesscommunication apparatus 11, data format information indicating a dataformat of the transmission data, and the like, are supplied from theequipment control unit 23 to the network managing unit 53 via theinterface 51.

Note that the communication partner information is information regardingthe wireless communication apparatus which is a destination of thetransmission data, and, for example, it can be specified from thecommunication partner information what kind of configuration of thetransmission frame, such as a transmission frame having theconfiguration illustrated in FIG. 10, can be received by the wirelesscommunication apparatus which becomes a communication partner.

The network managing unit 53 acquires the destination information, thecommunication partner information, and the data format informationsupplied in this manner, and supplies these kinds of information to thetransmission frame constructing unit 54 and the wireless communicationcontrol unit 55 as necessary. Further, the wireless communicationcontrol unit 55 supplies necessary information to the header informationgenerating unit 56, the preamble generating unit 57, the inter-traininggenerating unit 58, the transmission power control unit 59, and thelike, on the basis of the destination information, the communicationpartner information, and the data format information supplied from thenetwork managing unit 53.

The transmission frame constructing unit 54 constructs (generates) datain a unit of MPDU (hereinafter, also referred to as MPDU data) from thetransmission data held in the transmission buffer 52 using theinformation supplied from the network managing unit 53 as necessary andsupplies the MPDU data to the wireless transmission processing unit 60.That is, the transmission data is stored in the MPDU and supplied to thewireless transmission processing unit 60.

In this event, for example, the transmission frame constructing unit 54generates MAC header information of the head of the MPDU data on thebasis of the destination information and the data format informationsupplied from the network managing unit 53. Specifically, for example,address information included in the MAC header information is generatedon the basis of the destination information.

These kinds of MPDU data correspond to MPDU-1 and MPDU-2 illustrated in,for example, FIG. 10 and FIG. 11. Note that the transmission frameconstructing unit 54 also generates delimiter information as necessaryas well as the MPDU data and supplies the delimiter information to thewireless transmission processing unit 60.

In step S13, the wireless communication control unit 55 acquiresinformation regarding a frequency channel which can be utilized forwireless communication.

For example, the wireless communication control unit 55 acquiresbandwidth information indicating a bandwidth of the received frame andspatial multiplexed stream number information, supplied from the headerinformation analyzing unit 67, and information for generating channelmap information supplied from the network managing unit 53, asinformation regarding a frequency channel which can be utilized forwireless communication. Here, the bandwidth information and the spatialmultiplexed stream number information of the received frame are read outfrom the preamble of the received frame detected at the preambledetecting unit 66.

In addition, for example, in a case where the inter-training signal isdetected from the received frame, the channel map information, or thelike, read out from the inter-training signal may be acquired as theinformation regarding the frequency channel which can be utilized forwireless communication.

For example, the wireless communication control unit 55 can specify ausage situation of the wireless transmission path (frequency band) suchas what kind of frequency channel exists as the frequency band(frequency channel) which can be utilized for wireless communication,and which frequency channel is available, that is, an available channelwhich is not used for transmission of the transmission frame, byreferring to the channel map information, or the like.

Therefore, the wireless communication control unit 55 can specifyavailable channels which are frequency channels which can be utilized bythe own apparatus from the channel map information, or the like, and cancontrol transmission of the own signal (transmission frame) by utilizingsome of the specified available channels.

In step S14, the wireless communication control unit 55 determineswhether or not there is a frequency channel (band) which is an availablechannel among the frequency bands of the wireless transmission path onthe basis of the information regarding the frequency channel which canbe utilized, acquired in the processing in step S13.

In a case where it is determined in step S14 that there is no availablechannel, because all frequency channels are utilized, and the owntransmission frame cannot be transmitted, the processing returns to stepS13, and the above-described processing is repeatedly performed.

In contrast, in a case where it is determined in step S14 that there isan available channel, in step S15, the wireless communication controlunit 55 sets a channel width to be utilized and a channel of thetransmission frame.

That is, the wireless communication control unit 55 selects a frequencychannel to be utilized for transmission of the transmission frame, thatis, a frequency channel to be utilized by the own apparatus, among theavailable channels. Further, the wireless communication control unit 55sets a bandwidth to be utilized for transmission of the transmissionframe, that is, whether or not to bundle frequency channels, how manyfrequency channels should be bundled, and the like.

For example, here, a channel width (bandwidth) and a frequency channelto be utilized for transmission of the transmission frame are determinedfrom a transmission destination of the transmission frame, that is,combination of a frequency channel which can be utilized by the wirelesscommunication apparatus which receives the transmission frame, and afrequency channel which is not utilized by other wireless communicationapparatuses at the present moment, in accordance with predeterminedalgorithm.

By this means, for example, as in the example illustrated in FIG. 10 andFIG. 11, which frequency channel is utilized and how the frequencychannel is used are determined such as two frequency channels whosebandwidths are 20 MHz being bundled to be utilized as one broadbandchannel whose bandwidth is 40 MHz.

In step S16, the header information generating unit 56 sets parametersof the header information on the basis of the information supplied fromthe transmission frame constructing unit 54, the information suppliedfrom the wireless communication control unit 55, or the like.

That is, the header information generating unit 56 generates the L-SIGhaving the configuration illustrated in, for example, FIG. 6, copies theL-SIG to be set as an RL-SIG, and, further, generates an HE-SIG-A havingthe configuration illustrated in, for example, FIG. 7, and suppliesthese kinds of information to the preamble generating unit 57. Further,the header information generating unit 56 generates information such asthe L-STF, the L-LTF, the HE-STF, and the HE-LTF on the basis of theinformation supplied from the wireless communication control unit 55, orthe like, and supplies these kinds of information to the preamblegenerating unit 57.

Then, the preamble generating unit 57 generates a preamble for eachfrequency channel to be utilized for transmission of the transmissionframe using the information supplied from the wireless communicationcontrol unit 55 as necessary as well as the information supplied fromthe header information generating unit 56, and supplies the preamble tothe wireless transmission processing unit 60. By this means, thepreamble (preamble signal) having the configuration illustrated in FIG.10 in which, for example, the L-STF, the L-LTF, the L-SIG, the RL-SIG,the HE-SIG-A, the HE-STF, and a predetermined number of HE-LTFs aresequentially arranged, is generated.

Further, the preamble generating unit 57 supplies part or all of theinformation used for generation of the preamble to the inter-traininggenerating unit 58.

In step S17, the wireless communication control unit 55 determineswhether or not to transmit the inter-training signal.

For example, in a case where an OBSS which overlaps with the own BSSexists around the apparatus from the BSS Color information, or the like,included in the header information of the received frame supplied fromthe header information analyzing unit 67, that is, in a case where areceived frame of the OBSS is detected, the wireless communicationcontrol unit 55 determines to transmit the inter-training signal.

Further, for example, it is also possible to determine to transmit theinter-training signal in a case where transmission data (MPDU) istransmitted in a plurality of frequency channels, that is, in a casewhere a plurality of frequency channels is utilized by the wirelesscommunication apparatus 11 itself, or the wireless communicationapparatus 11 and other wireless communication apparatuses. In thisevent, examples of a situation where a plurality of frequency channelsis utilized can include a case where, for example, each piece oftransmission data (MPDU) is transmitted by each of the plurality offrequency channels, a case where the plurality of frequency channels isbundled to be set as one broadband frequency channel, and thetransmission data is transmitted in the one broadband frequency channel.

In a case where it is determined in step S17 not to transmit theinter-training signal, the processing from steps S18 to S20 is skipped,and the processing proceeds to step S21.

In contrast, in a case where it is determined in step S17 to transmitthe inter-training signal, in step S18, the wireless communicationcontrol unit 55 sets a frequency channel to be utilized for transmissionof the inter-training signal.

For example, the wireless communication control unit 55 selects at leastone of the frequency channels which are determined as available channelsas a result of the processing in step S14, as a frequency channel to beutilized for transmission of the inter-training signal, that is, themanagement channel while the setting result in step S15 is taken intoaccount. In this event, for example, as illustrated in FIG. 11, in acase where the management channel is switched over time, a plurality offrequency channels is selected as the management channel.

In step S19, the inter-training generating unit 58 sets parameters(information) included in the inter-signal information (Inter-SIG) inaccordance with control by the wireless communication control unit 55.That is, for example, what kind of parameters such as various kinds ofparameters (information) illustrated in FIG. 12 is included in theinter-signal information, is determined.

In step S20, the inter-training generating unit 58 sets a transmissioninterval and a transmission pattern of the inter-training signal inaccordance with control by the wireless communication control unit 55.

That is, the inter-training generating unit 58 determines a length of aperiod from when a predetermined inter-training signal is transmitteduntil the next inter-training signal is transmitted as the transmissioninterval. Here, the transmission interval may be changed over time. Thatis, the inter-training signal may be transmitted at irregular intervals.

Further, as in the example illustrated in, for example, FIG. 11, in acase where the management channel is changed over time, theinter-training generating unit 58 determines a pattern of the change asthe transmission pattern while the setting result in step S15 is takeninto account.

In a case where the processing in step S20 is performed, or in a casewhere it is determined in step S17 not to transmit the inter-trainingsignal, processing in step S21 is performed.

In step S21, the transmission power control unit 59 determines whetheror not to adjust transmission power on the basis of received power ofthe received frame received by the wireless communication apparatus 11,supplied from the wireless reception processing unit 63 via thedetection threshold control unit 64, the BSS Color information read outfrom the preamble, or the like, of the received frame, or the like. Thatis, it is determined whether or not it is necessary to adjusttransmission power of the transmission frame.

Specifically, for example, in a case where a received frame of the OBSSwhose received power is equal to or greater than predetermined receivedpower is detected, it is determined that it is necessary to adjusttransmission power of the transmission frame.

In step S21, in a case where it is determined not to adjust thetransmission power, processing in step S22 is not performed, and,thereafter, the processing proceeds to step S23. In this case, forexample, the transmission frame is transmitted at transmission power, orthe like, indicated by a transmission power value determined in advance.

In contrast, in a case where it is determined in step S21 to adjust thetransmission power, in step S22, the transmission power control unit 59controls (adjusts) transmission power of the transmission frame bysetting a transmission power value of the transmission frame.

For example, the transmission power control unit 59 determines thetransmission power of the transmission frame on the basis of thereceived power, or the like, of the received frame received by thewireless communication apparatus 11, supplied from the wirelessreception processing unit 63 via the detection threshold control unit64. Here, the received power of the received frame is received powerindicated by, for example, received field strength information obtainedin step S61 in FIG. 15 which will be described later.

In addition, for example, the transmission power of the transmissionframe may be determined on the basis of the BSS Color information, thetransmission power control level (TPC Level), the receiving sensitivitycontrol level (DSC Level), or the like, read out from the inter-trainingsignal of the received frame.

In this case, for example, it is possible to set the transmission powerof the own transmission frame so as not to affect the communication inthe OBSS, from the BSS to which the apparatus of the transmission sourceof the received frame indicated by the BSS Color information belongs andthe received power of the received frame.

In a case where the transmission power value is set in the processing instep S22 or it is determined in step S21 not to adjust the transmissionpower, the processing in step S23 is performed.

That is, in step S23, the wireless communication control unit 55acquires NAV information indicating a period during which transmissionof a signal for the own BSS is inhibited, that is, a period during whichthe transmission frame cannot be transmitted.

Specifically, in a case where the transmission frame transmitted fromother wireless communication apparatuses is received as the receivedframe at the wireless communication apparatus 11, it is possible toobtain the BSS Color information stored in the preamble and theinter-training signal of the received frame.

That is, the wireless communication control unit 55 can specify whetherthe received frame is a signal of the BSS or a signal of the OBSS fromthe BSS Color information stored in the header information or theinter-signal information, supplied from the header information analyzingunit 67.

Further, when the received frame is a signal of the BSS, the wirelesscommunication control unit 55 can specify a timing at which transmissionof the MPDU data, that is, the received frame is completed, and, furthera timing for receiving an ACK frame, from the Duration informationstored in the MAC header information of the MPDU data extracted from thereceived frame and supplied from the received data constructing unit 68via the network managing unit 53.

On the basis of a result of specifying a timing at which transmission ofthe received frame is completed, the wireless communication control unit55 generates NAV information indicating a period required to enable theown apparatus to start transmitting the transmission frame after thetiming from the current time, as NAV information of the own BSS. SuchNAV information can be said as information indicating a communicationsituation in the BSS.

Note that it is also possible to reset the NAV information every timethe MPDU data is newly received. Further, length information, or thelike, extracted from the header information and the inter-trainingsignal of the received frame may be used for generation of the NAVinformation.

Here, a value of the NAV information of the BSS is decremented by oneevery time a predetermined time period elapses, and, when the value ofthe NAV information becomes 0, it becomes possible to transmit the owntransmission frame.

In step S24, the wireless communication control unit 55 determineswhether or not to transmit the transmission frame using advanced spatialreuse.

In a case where it is determined in step S24 to transmit thetransmission frame using advanced spatial reuse, in step S25, thewireless communication control unit 55 acquires the NAV information ofthe OBSS.

That is, the wireless communication control unit 55 generates the NAVinformation of the OBSS from the length information, the Durationinformation, or the like, obtained from the preamble, the inter-trainingsignal, or the like, of the received frame which is determined as asignal of the OBSS in a similar manner to upon acquisition of the NAVinformation of the BSS in step S23. If the NAV information of the OBSScan be obtained, thereafter, the processing proceeds to step S26.

In this manner, the wireless communication apparatus 11 can efficientlyperform communication using advanced spatial reuse by specifying whetherthe received frame is a signal of the BSS or the OBSS, or the like, byacquiring the BSS Color information from the received frame andobtaining the NAV information of the BSS and the OBSS.

In the present technology, because the BSS Color information specifyingthe BSS and the OBSS is also stored in the inter-training signal as wellas in the preamble, even if reception is performed in the middle of thereceived frame, it is possible to specify whether the received frame isa signal of the BSS or a signal of the OBSS.

Therefore, the wireless communication control unit 55 can obtain NAVinformation indicating a communication situation of each of the wirelessnetworks concerning the BSS and each OBSS. In other words, the wirelesscommunication control unit 55 can individually manage communicationsituations of the wireless networks for each of the wireless networksusing the NAV information, that is, on the basis of the BSS Colorinformation, the length information, and the Duration information.

Note that, in step S25, the NAV information of the OBSS may be generatedonly in a case where the wireless communication apparatus 11 is in adense environment where a number of wireless communication apparatusesexist around the wireless communication apparatus 11, and it ispredicted that traffic becomes crowded.

Meanwhile, in a case where it is determined in step S24 not to transmitthe transmission frame using the advanced spatial reuse, the processingthereafter proceeds to step S26.

If it is determined in step S24 not to transmit the transmission frameusing the advanced spatial reuse, or processing in step S25 isperformed, processing in step S26 is performed.

That is, in step S26, the wireless communication control unit 55determines whether or not transmission right of the transmission frameis acquired on the basis of the NAV information.

Basically, if, for example, values of all the NAV information on thewireless transmission path become 0, and a signal having received powerequal to or greater than a threshold of predetermined received fieldstrength (received power) is not detected during an inter-frame spaceperiod, it is determined that transmission right is acquired.

Further, for example, in a case where the transmission frame istransmitted using the advanced spatial reuse, even if a value of the NAVinformation of the OBSS is not 0, if the value of the NAV information ofthe BSS is 0, and it is possible to transmit the transmission framewithout affecting the OBSS, it may be determined that the transmissionright is acquired.

Specifically, it is, for example, assumed that the received framereceived by the wireless communication apparatus 11 is a signal of theOBSS, and the received power is equal to or less than predeterminedpower. In this case, the wireless communication control unit 55determines that the transmission right of the transmission frame isacquired, and controls transmission of the transmission frame by thewireless transmission processing unit 60 so that the transmission frameis transmitted at transmission power determined by the transmissionpower control unit 59.

In a case where it is determined in step S26 that the transmission rightis not acquired, the wireless communication control unit 55 decrementseach of the held value of the NAV information of the BSS and the heldvalue of the NAV information of the OBSS by one after a predeterminedperiod has elapsed, and, thereafter, the processing returns to step S26.That is, the processing in step S26 is repeatedly performed until thetransmission right is acquired.

In contrast, in a case where it is determined in step S26 that thetransmission right is acquired, in step S27, the wireless transmissionprocessing unit 60 transmits the MPDU of the transmission frame.

That is, in a case of a head portion of the transmission frame, thewireless transmission processing unit 60 performs processing ofconverting into a baseband signal, modulation processing, or the like,on the preamble supplied from the preamble generating unit 57, andsupplies a transmission signal obtained as a result to the antennacontrol unit 61. In this event, the preamble (preamble signal) istransmitted for each frequency channel.

Further, after transmission of the preamble signal, the wirelesstransmission processing unit 60 performs processing of converting into abaseband signal, modulation processing, or the like, on the MPDU datasupplied from the transmission frame constructing unit 54, and suppliesa transmission signal obtained as a result to the antenna control unit61.

The antenna control unit 61 causes the transmission signal supplied fromthe wireless transmission processing unit 60 to be output from theantenna 62. In this event, when transmission power is adjusted, thewireless transmission processing unit 60 and the antenna control unit 61operate so that the transmission signal, that is, the preamble and theMPDU data of the transmission frame are transmitted at transmissionpower indicated by the transmission power value set in step S22 or thelike, in accordance with control by the transmission power control unit59.

Through the processing in step S27, of the transmission frame, a portionof the preamble which is the head portion of the transmission frame, anda portion of the MPDU subsequent to the preamble are transmitted. Inthis event, for example, in a case where a plurality of frequencychannels is bundled to be utilized as one broadband channel, the MPDUdata is transmitted by utilizing a band of the channel.

Note that, in a case where the delimiter information is also transmittedalong with the MPDU data, after the delimiter information istransmitted, the MPDU data arranged immediately after the delimiterinformation is transmitted.

In step S28, the inter-training generating unit 58 determines whether ornot it is a timing for transmitting the inter-training signal on thebasis of the transmission interval and the transmission pattern of theinter-training signal determined in the processing in step S20.

In step S28, in a case where it is determined that it is not yet atiming for transmitting the inter-training signal, the processingreturns to step S28, and the above-described processing is repeatedlyperformed.

Meanwhile, in a case where it is determined in step S28 that it is atiming for transmitting the inter-training signal, in step S29, theinter-training generating unit 58 acquires parameters of theinter-signal information (Inter-SIG).

That is, the inter-training generating unit 58 acquires parameters ofthe inter-signal information (Inter-SIG) determined in the processing instep S19 from the preamble generating unit 57 and the wirelesscommunication control unit 55, and generates the inter-signalinformation from the acquired parameters. Here, for example, informationregarding a remaining period of an A-MPDU, that is, respectiveparameters (information) illustrated in FIG. 12, such as the lengthinformation, the BSS Color information, and the channel map informationare acquired, and the inter-signal information (Inter-SIG) having theconfiguration illustrated in FIG. 12 is generated.

Further, the inter-training generating unit 58 generates theinter-training signal by arranging information such as the L-STF, theL-LTF, and the L-SIG supplied from the preamble generating unit 57 andthe wireless communication control unit 55, and the generatedinter-signal information. By this means, for example, the inter-trainingsignal having the configuration illustrated in FIG. 10 can be obtained.

The inter-training generating unit 58 supplies the inter-training signalgenerated in this manner to the wireless transmission processing unit60.

In step S30, the wireless transmission processing unit 60 transmits theinter-training signal of the transmission frame.

That is, the wireless transmission processing unit 60 performsprocessing of converting into a baseband signal, modulation processing,or the like, on the inter-training signal supplied from theinter-training generating unit 58 and supplies the transmission signalobtained as a result to the antenna control unit 61.

Further, the antenna control unit 61 causes the transmission signalsupplied from the wireless transmission processing unit 60 to be outputfrom the antenna 62.

In this event, the wireless transmission processing unit 60 and theantenna control unit 61 operate so that the transmission signal, thatis, the inter-training signal of the transmission frame is transmittedat transmission power indicated by the transmission power value set instep S22 or the like, in accordance with control by the transmissionpower control unit 59.

Through the processing as described above, at the wireless communicationapparatus 11, during a transmission period of the MPDU data, that is,while the MPDU data is transmitted, the inter-training signal istransmitted at the transmission interval and with the transmissionpattern set in step S20.

That is, the wireless transmission processing unit 60 transmits the nextinter-training signal after a predetermined period indicated by thetransmission interval has elapsed since the immediately precedinginter-training signal had been transmitted. In this event, the wirelesstransmission processing unit 60 switches a frequency channel to beutilized for transmission of the inter-training signal as necessary overtime in accordance with the transmission pattern.

As a result, for example, the inter-training signal is stored in thetransmission frame with a pattern illustrated in FIG. 10 or FIG. 11, andthe transmission frame including the inter-training signal istransmitted.

In step S31, the wireless communication control unit 55 determineswhether or not a tail end of the MPDU data has been reached for theindividual pieces of the MPDU data transmitted using the respectivefrequency channels.

In step S31, in a case where it is determined that any tail end of theMPDU data has not been reached, that is, all the MPDU data is beingtransmitted, the processing returns to step S28, and the above-describedprocessing is repeatedly performed. That is, transmission of the MPDU iscontinuously performed, and the inter-training signal is repeatedlytransmitted at determined transmission intervals.

In contrast, in a case where it is determined in step S31 that the tailend of the MPDU data has been reached, in step S32, the wirelesscommunication control unit 55 determines whether or not a tail end ofthe A-MPDU has been reached, that is, whether or not a tail end of thetransmission frame has been reached.

In a case where it is determined in step S32 that the tail end has notbeen reached, because the MPDU data and the inter-training signal arestill transmitted, the processing returns to step S27, and theabove-described processing is repeatedly performed.

In contrast, in a case where it is determined in step S32 that the tailend has been reached, in step S33, the wireless reception processingunit 63 receives an ACK frame.

That is, when the transmission frame transmitted by the wirelesscommunication apparatus 11 is received by a wireless communicationapparatus of a communication partner, the wireless communicationapparatus of the communication partner transmits an ACK frame to thewireless communication apparatus 11.

In a case where received power of the received frame supplied from theantenna 62 via the antenna control unit 61 is equal to or greater thanthe detection threshold supplied from the detection threshold controlunit 64, the wireless reception processing unit 63 regards the receivedframe as being received. That is, detection of the preamble and theinter-training signal is performed for the received frame.

The preamble detecting unit 66 detects the preamble from the receivedframe by detecting a predetermined sequence pattern which is a preambleportion from the received frame received at the wireless receptionprocessing unit 63. If the preamble is detected, the preamble detectingunit 66 supplies the detection result to the wireless communicationcontrol unit 55 and the header information analyzing unit 67.

The header information analyzing unit 67 extracts the headerinformation, or the like, from the received frame received at thewireless reception processing unit 63 in accordance with the detectionresult supplied from the preamble detecting unit 66 and supplies theheader information, or the like, to the received data constructing unit68.

Further, the received data constructing unit 68 extracts the receiveddata stored in the MPDU data from the received frame received at thewireless reception processing unit 63 on the basis of the headerinformation, or the like, supplied from the header information analyzingunit 67 and supplies the received data to the reception buffer 69 andthe network managing unit 53.

In a case where the received frame received in this manner is the ACKframe, because information indicating which received data, that is,which MPDU data is correctly received can be obtained, the networkmanaging unit 53 supplies the information obtained from the ACK frame tothe wireless communication control unit 55.

In step S34, the wireless communication control unit 55 determineswhether or not the ACK frame indicating that all the transmittedtransmission data (MPDU data) of the transmission frame is correctlyreceived, is received.

For example, in a case where information indicating that all the MPDUdata included in the transmitted transmission frame is correctlyreceived is supplied from the network managing unit 53, the wirelesscommunication control unit 55 determines that the ACK frame indicatingthat all the MPDU data of the transmission frame is correctly receivedis received. By this means, the transmission frame is correctly receivedby the wireless communication apparatus of the communication partner.

In a case where it is determined in step S34 that the ACK frameindicating that all the MPDU data of the transmission frame is correctlyreceived is not received, the processing returns to step S16, and theabove-described processing is repeatedly performed.

In this case, while the transmission frame is retransmitted because thetransmission frame is not correctly received, because transmission poweris appropriately controlled in step S22 as necessary upon theretransmission, communication is performed more efficiently.

In contrast, in a case where it is determined in step S34 that the ACKframe indicating that all the MPDU data of the transmission frame iscorrectly received is received, because the transmission frame iscorrectly received on the communication partner side, the transmissionprocessing is finished.

As described above, the wireless communication apparatus 11 transmitsthe transmission frame in which part of the header information is storedin the inter-training signal. By this means, it is possible to performcommunication more efficiently.

(Description of Reception Processing)

Subsequently, reception processing to be performed when the wirelesscommunication apparatus 11 receives the received frame transmitted fromthe communication partner will be described. That is, receptionprocessing by the wireless communication apparatus 11 will be describedbelow with reference to the flowchart in FIG. 15.

When the reception processing is started, the wireless communicationapparatus 11 first causes operation of each block which functions as areceiver of the own apparatus to start, to receive the received frameaddressed to the own apparatus.

Then, in step S61, the wireless reception processing unit 63 detectsreceived power of the received frame supplied from the antenna 62 viathe antenna control unit 61, that is, received field strength, andobtains received field strength information indicating the receivedpower (signal detection level).

In this event, for example, if the received power of the received frameobtained (detected) by the wireless reception processing unit 63 isequal to or greater than the detection threshold supplied from thedetection threshold control unit 64, detection of the preamble and theinter-training signal is performed for the received frame. Note that,more particularly, detection of the preamble and the inter-trainingsignal is performed also for a received frame whose received power isless than the detection threshold.

The inter-training detecting unit 65 detects the inter-training signalfrom the received frame by detecting a predetermined sequence pattern ofthe inter-training signal portion from the received frame received atthe wireless reception processing unit 63. Here, processing of detectingthe inter-training signal from the received signal (received frame) isperformed for the entire band constituting the frequency band which canbe utilized for wireless communication, that is, all the frequencychannels.

Further, the preamble detecting unit 66 detects a preamble from thereceived frame by detecting a predetermined sequence pattern of thepreamble portion from the received frame received at the wirelessreception processing unit 63.

Note that, at the detection threshold control unit 64, processing ofsetting the preamble detection threshold of the BSS from a predeterminedreceived field strength level, and determining a detection thresholdOBSS_PD in accordance with a maximum value and a minimum value of thedetection threshold determined in advance on the basis of thetransmission power of the frame to be transmitted for the preambledetection threshold of the OBSS, is performed.

For example, preamble detection is first determined from the thresholdof the received power of the received frame, and, thereafter, in a casewhere it is determined that the received frame is a signal from theOBSS, determination of the detection threshold of OBSS_PD is performedin accordance with the transmission power of the frame to betransmitted.

Here, the received power of the received frame of the BSS or the OBSSsupplied from the wireless reception processing unit 63 is receivedpower indicated by the received field strength information obtained inthe processing in step S61. It is possible to specify whether thereceived power indicated by this received field strength information isa signal of the BSS or a signal of the OBSS, from the BSS Colorinformation supplied from the wireless communication control unit 55.

In step S62, the preamble detecting unit 66 determines whether or notthe preamble is detected from the received frame.

In a case where it is determined in step S62 that the preamble isdetected, the preamble detecting unit 66 supplies the detection resultto the wireless communication control unit 55 and the header informationanalyzing unit 67, and the processing proceeds to step S63.

In step S63, the header information analyzing unit 67 extracts theheader information, or the like, from the detected preamble on the basisof the detection result supplied from the preamble detecting unit 66,supplies the header information, or the like, to the wirelesscommunication control unit 55 and the received data constructing unit68, and, thereafter, the processing proceeds to step S66. By this means,a PLCP header, that is, the header information formed with the L-SIG,the RL-SIG, and the HE-SIG-A is extracted from the preamble of thereceived frame.

In contrast, in a case where it is determined in step S62 that thepreamble is not detected, in step S64, the inter-training detecting unit65 determines whether or not the inter-training signal is detected fromthe received frame.

In a case where it is determined in step S64 that the inter-trainingsignal is detected, the inter-training detecting unit 65 supplies thedetection result of the inter-training signal to the header informationanalyzing unit 67, and, thereafter, the processing proceeds to step S65.

In step S65, the header information analyzing unit 67 extracts variouskinds of parameters from the inter-training signal of the received framereceived at the wireless reception processing unit 63 on the basis ofthe detection result supplied from the inter-training detecting unit 65,and, thereafter, the processing proceeds to step S66.

That is, the header information analyzing unit 67 extracts various kindsof parameters stored in the L-SIG and the inter-signal information(Inter-SIG) from the inter-training signal and supplies the variouskinds of parameters to the wireless communication control unit 55 andthe received data constructing unit 68.

Because the header information analyzing unit 67 can obtain the BSSColor information, or the like, for example, as the parameters stored inthe inter-signal information, even when the received frame is detectedin the middle of the frame, it is possible to specify whether thereceived frame is a signal of the BSS or a signal of the OBSS, so thatit is possible to perform communication more efficiently.

In addition, because it is possible to obtain parameters, or the like,regarding the advanced spatial reuse technology from the inter-signalinformation, even when the received frame is received in the middle ofthe frame, it is possible to decode the received frame, that is, extractthe received data. Further, because it is possible to obtain channel mapinformation, or the like, from the inter-signal information, even whenthe received frame is received in the middle of the frame, the wirelesscommunication control unit 55 can specify (recognize) a usage situationof the wireless transmission path, that is, the frequency channels.

Further, if the preamble and the inter-training signal are detected fromthe received frame, the received data constructing unit 68 analyzes theMAC header information stored in the MPDU data from the received framereceived at the wireless reception processing unit 63 on the basis ofthe header information, or the like, supplied from the headerinformation analyzing unit 67. By this means, it is possible to obtainaddress information indicated by characters “Address” within the MACheader information illustrated in, for example, FIG. 8, and the receiveddata constructing unit 68 supplies the obtained address information tothe wireless communication control unit 55 via the network managing unit53.

If the processing in step S63 or step S65 is performed, in step S66, thewireless communication control unit 55 determines whether or not thereceived frame received is a signal of the own BSS.

For example, the wireless communication control unit 55 determines thatthe received frame is a signal of the own BSS in a case where the BSSColor information read out from the header information and theinter-signal information supplied from the header information analyzingunit 67 is information indicating the BSS to which the wirelesscommunication apparatus 11 belongs.

In a case where it is determined in step S66 that the received frame isa signal of the own BSS, in step S67, the wireless communication controlunit 55 determines whether or not the received frame received is data(received frame) addressed to the own apparatus.

For example, in a case where the address information supplied from thereceived data constructing unit 68 via the network managing unit 53indicates the own apparatus, that is, the wireless communicationapparatus 11, the wireless communication control unit 55 determines thatthe received frame is data addressed to the own apparatus. Further, forexample, it may be determined whether the received frame is dataaddressed to the own apparatus from information of part of the address(AID12) indicating the wireless communication apparatus of atransmission source or a recipient of the transmission frame, or thelike, read out from the inter-signal information.

In a case where it is determined in step S67 that the received frame isdata addressed to the own apparatus, the processing proceeds to stepS68.

In step S68, the received data constructing unit 68 extracts receiveddata stored in one piece of the MPDU data from the received framereceived at the wireless reception processing unit 63 on the basis ofthe header information, the delimiter information, or the like, suppliedfrom the header information analyzing unit 67. That is, the receiveddata is extracted in units of the MPDU.

The received data constructing unit 68 supplies the extracted receiveddata to the network managing unit 53 and the reception buffer 69. Thereceived data held at the reception buffer 69 is supplied to theequipment control unit 23 via the interface 51.

In step S69, the received data constructing unit 68 determines whetheror not the MPDU data, that is, the received data in units of the MPDUcan be correctly received as a result of step S68.

In a case where it is determined in step S69 that the MPDU data can becorrectly received, in step S70, the received data constructing unit 68constructs (generates) ACK information indicating that the MPDU data iscorrectly received, and supplies the ACK information to the wirelesscommunication control unit 55 via the network managing unit 53. If theACK information is generated, thereafter, the processing proceeds tostep S71.

In contrast, in a case where it is determined in step S69 that the MPDUdata cannot be correctly received, the processing in step S70 is notperformed, and, thereafter, the processing proceeds to step S71.

In a case where it is determined in step S69 that the MPDU data cannotbe correctly received or the processing in step S70 is performed,thereafter, the processing in step S71 is performed.

That is, in step S71, the wireless communication control unit 55determines whether or not a tail end of the aggregated A-MPDU has beenreached, that is, whether or not a tail end of the received frame hasbeen reached, on the basis of the header information, or the like,supplied from the header information analyzing unit 67.

In a case where it is determined in step S71 that the tail end of theA-MPDU has not been reached yet, the processing returns to step S68, andthe above-described processing is repeatedly performed.

In contrast, in a case where it is determined in step S71 that the tailend of the A-MPDU has been reached, in step S72, the wirelesstransmission processing unit 60 transmits an ACK frame.

That is, the wireless communication control unit 55 controls the headerinformation generating unit 56 and the preamble generating unit 57 onthe basis of the ACK information supplied from the received dataconstructing unit 68 to generate the preamble of the ACK frame. Thepreamble generating unit 57 generates the preamble using the informationsupplied from the header information generating unit 56 and the wirelesscommunication control unit 55 as necessary and supplies the preamble tothe wireless transmission processing unit 60.

Further, the network managing unit 53 controls the transmission frameconstructing unit 54 as necessary on the basis of the ACK informationsupplied from the received data constructing unit 68 to generate andsupply the MPDU data of the ACK frame to the wireless transmissionprocessing unit 60.

The wireless transmission processing unit 60 performs processing ofconverting into a baseband signal, modulation processing, or the like,on the ACK frame formed with the preamble supplied from the preamblegenerating unit 57 and the MPDU data supplied from the transmissionframe constructing unit 54, and supplies the ACK frame obtained as aresult to the antenna control unit 61.

Further, the antenna control unit 61 causes the ACK frame supplied fromthe wireless transmission processing unit 60 to be output from theantenna 62. In this event, the wireless transmission processing unit 60and the antenna control unit 61 operate so that the ACK frame istransmitted at transmission power, for example, set through processingin step S22 in FIG. 14, or the like, in accordance with control by thetransmission power control unit 59.

For example, the information indicating the correctly received MPDU datais included in the ACK frame to be transmitted by the wirelesstransmission processing unit 60. When the ACK frame is transmitted inthis manner, the reception processing is finished.

Further, in a case where it is determined in step S67 that the receivedframe is not data addressed to the own apparatus, that is, in a casewhere, while the BSS Color information included in the received frame isinformation indicating the own BSS, the received frame is not addressedto the own apparatus, the processing proceeds to step S73.

In step S73, the wireless communication control unit 55 sets or updatesthe NAV information of the own BSS.

That is, in a case where the wireless communication control unit 55 doesnot hold the NAV information of the own BSS, the wireless communicationcontrol unit 55 generates NAV information of the own BSS in a similarmanner to a case in step S23 in FIG. 14.

For example, the NAV information of the BSS is generated from theDuration information stored in the MAC header information of the MPDUdata supplied from the received data constructing unit 68 via thenetwork managing unit 53, the length information supplied from theheader information analyzing unit 67, or the like.

Further, in a case where the wireless communication control unit 55 hasalready held the NAV information of the own BSS, the wirelesscommunication control unit 55 updates the held NAV information on thebasis of the Duration information, or the like, stored in the MAC headerinformation of the newly received MPDU data.

In a case where, while the BSS Color information included in thereceived frame is information indicating the own BSS, the received frameis not addressed to the own apparatus, communication for transmissionand reception of the received frame is performed for a period indicatedby the Duration information stored in the MAC header information.

In a case where the NAV information of the own BSS is generated orupdated in this manner, thereafter, the processing proceeds to step S78.

Further, in a case where it is determined in step S66 that the receivedframe is not a signal of the own BSS, in step S74, the wirelesscommunication control unit 55 determines whether or not the receivedframe received is a signal of the OBSS.

For example, in a case where the BSS Color information included in theheader information and the inter-signal information is supplied from theheader information analyzing unit 67, the wireless communication controlunit 55 determines that the received frame is a signal of the OBSS ifthe BSS Color information is information indicating other BSSs to whichthe wireless communication apparatus 11 does not belong, that is, theOBSS.

In a case where it is determined in step S74 that the received frame isa signal of the OBSS, in step S75, the wireless communication controlunit 55 sets or updates the NAV information of the OBSS.

That is, in step S75, the NAV information of the OBSS is generated orupdated by processing similar to that in step S73 being performed. Notethat the NAV information of the OBSS may be generated for each OBSS, oronly NAV information of the OBSS whose duration is the longest among aplurality of OBSSs may be set (generated) and managed.

By managing the NAV information for each of the wireless networks forthe BSS and the respective OBSSs also upon reception processing in asimilar manner to upon transmission processing, the wirelesscommunication control unit 55 can individually manage the communicationsituations of the respective wireless networks using the NAVinformation.

When the NAV information of the OBSS is set or updated, thereafter, theprocessing proceeds to step S78.

Meanwhile, in a case where it is determined in step S74 that thereceived frame is not a signal of the OBSS, thereafter, the processingproceeds to step S77.

Further, in a case where it is determined in step S64 that theinter-training signal has not been detected, the processing proceeds tostep S76.

In step S76, the wireless communication control unit 55 determineswhether or not the received power of the received frame received at thewireless reception processing unit 63 is greater than the detectionthreshold determined at the detection threshold control unit 64.

In a case where it is determined in step S76 that the received power isgreater than the detection threshold, thereafter, the processingproceeds to step S77.

In a case where it is determined in step S76 that the received power isgreater than the detection threshold, or in a case where it isdetermined in step S74 that the received frame is not a signal of theOBSS, processing in step S77 is performed. That is, in step S77, thewireless communication control unit 55 regards the state as a statewhere carrier detection is being performed, and, thereafter, theprocessing proceeds to step S78.

In this case, while neither the preamble nor the inter-training signalhas been detected for the received frame, because a signal having greatreceived power is detected, the state is regarded as a state wherecarrier detection is being performed, and processing of detecting thepreamble and the inter-training signal from the signal being received(received frame) is continuously performed. Note that, in a state wherecarrier detection is being performed, the wireless communicationapparatus 11 cannot transmit the transmission frame.

In contrast, in a case where it is determined in step S76 that thereceived power is equal to or less than the detection threshold, thestate is not regarded as a state where carrier detection is beingperformed, and, thereafter, the processing proceeds to step S78.

Further, in a case where the processing in step S73 is performed, theprocessing in step S75 is performed, the processing in step S77 isperformed, or it is determined in step S76 that the received power isequal to or less than the detection threshold, processing in step S78 isperformed.

That is, in step S78, the wireless communication control unit 55acquires all the NAV information. Specifically, the wirelesscommunication control unit 55 reads out the NAV information of the ownBSS obtained in step S73, and the NAV information of the OBSS obtainedin step S75, and recognizes communication situations of the BSS and theOBSS indicated by the NAV information.

In step S79, the wireless communication control unit 55 determineswhether or not a predetermined period has elapsed since the NAVinformation had been updated last.

In a case where it is determined in step S79 that the predeterminedperiod has not elapsed yet, the processing returns to step S61, and theabove-described processing is repeatedly performed.

In contrast, in a case where it is determined in step S79 that thepredetermined period has elapsed, in step S80, the wirelesscommunication control unit 55 subtracts one from respective values ofthe NAV information of the own BSS and the NAV information of the OBSS.That is, the values of the NAV information are decremented.

In step S81, the wireless communication control unit 55 determineswhether or not the values of all the NAV information become 0.

In a case where it is determined in step S81 that the values of all theNAV information do not become 0, the processing returns to step S61, andthe above-described processing is repeatedly performed.

In contrast, in a case where it is determined in step S81 that thevalues of all the NAV information become 0, the reception processing isfinished.

As described above, the wireless communication apparatus 11 detects theinter-training signal in which part of the header information is stored,from the received frame, and extracts the part of the header informationfrom the inter-training signal. By this means, it is possible to performcommunication more efficiently.

<Configuration Example of Computer>

Incidentally, the above-described series of processes may be performedby hardware or may be performed by software. In a case where the seriesof processes is performed by software, a program forming the software isinstalled into a computer. Here, examples of the computer include acomputer that is incorporated in dedicated hardware, a general-purposepersonal computer that can perform various types of function byinstalling various types of program, and the like.

FIG. 16 is a block diagram illustrating a configuration example of thehardware of a computer that performs the above-described series ofprocesses with a program.

In the computer, a CPU 501, read only memory (ROM) 502, and randomaccess memory (RAM) 503 are mutually connected by a bus 504.

Further, an input/output interface 505 is connected to the bus 504.Connected to the input/output interface 505 are an input unit 506, anoutput unit 507, a recording unit 508, a communication unit 509, and adrive 510.

The input unit 506 includes a keyboard, a mouse, a microphone, an imagesensor, and the like. The output unit 507 includes a display, a speaker,and the like. The recording unit 508 includes a hard disk, anon-volatile memory, and the like. The communication unit 509 includes anetwork interface, and the like. The drive 510 drives a removablerecording medium 511 such as a magnetic disk, an optical disc, amagneto-optical disk, and a semiconductor memory.

In the computer configured as described above, the CPU 501 loads aprogram that is recorded, for example, in the recording unit 508 ontothe RAM 503 via the input/output interface 505 and the bus 504, andexecutes the program, thereby performing the above-described series ofprocesses.

For example, programs to be executed by the computer (CPU 501) can berecorded and provided in the removable recording medium 511, which is apackaged medium or the like. In addition, programs can be provided via awired or wireless transmission medium such as a local area network, theInternet, and digital satellite broadcasting.

In the computer, by mounting the removable recording medium 511 onto thedrive 510, programs can be installed into the recording unit 508 via theinput/output interface 505. Programs can also be received by thecommunication unit 509 via a wired or wireless transmission medium, andinstalled into the recording unit 508. In addition, programs can beinstalled in advance into the ROM 502 or the recording unit 508.

Note that a program executed by the computer may be a program in whichprocesses are chronologically carried out in a time series in the orderdescribed herein or may be a program in which processes are carried outin parallel or at necessary timing, such as when the processes arecalled.

In addition, embodiments of the present technology are not limited tothe above-described embodiments, and various alterations may occurinsofar as they are within the scope of the present disclosure.

For example, the present technology can adopt a configuration of cloudcomputing, in which a plurality of devices shares a single function viaa network and performs processes in collaboration.

Furthermore, each step in the above-described flowcharts can be executedby a single device or shared and executed by a plurality of devices.

In addition, in a case where a single step includes a plurality ofprocesses, the plurality of processes included in the single step can beexecuted by a single device or shared and executed by a plurality ofdevices.

Additionally, the present technology may also be configured as below.

(1)

A wireless communication apparatus including:

a preamble generating unit configured to generate a preamble signalincluding header information;

an inter-training generating unit configured to generate aninter-training signal including at least part of information of theheader information; and

a wireless transmission processing unit configured to transmittransmission data after transmitting the preamble signal in at least oneor more frequency channels among a plurality of the frequency channelsand transmit a plurality of the inter-training signals by utilizing oneor a plurality of the frequency channels among the plurality of thefrequency channels during a transmission period of the transmissiondata.

(2)

The wireless communication apparatus according to (1),

in which the inter-training signal includes a training sequence includedin the preamble signal.

(3)

The wireless communication apparatus according to (1) or (2),

in which the inter-training signal includes at least one of informationregarding the frequency channels to be utilized for transmission of thetransmission data, information for identifying a wireless network towhich the wireless communication apparatus belongs, or informationregarding the transmission period of the transmission data.

(4)

The wireless communication apparatus according to any one of (1) to (3),

in which the inter-training signal includes at least one of coding andmodulation scheme information of a signal to be transmitted by thewireless transmission processing unit, transmission power information,receiving sensitivity information, information regarding a spatial reusetechnology, or information regarding a wireless communication apparatusof a recipient of a signal.

(5)

The wireless communication apparatus according to any one of (1) to (4),

in which the wireless transmission processing unit repeatedly transmitsthe inter-training signal by utilizing one of the frequency channels.

(6)

The wireless communication apparatus according to any one of (1) to (4),

in which the wireless transmission processing unit switches thefrequency channel to be utilized for transmission of the inter-trainingsignal over time.

(7)

The wireless communication apparatus according to any one of (1) to (6),

in which the wireless transmission processing unit transmits theinter-training signal before transmission of the transmission data orafter transmission of the transmission data in one of the frequencychannels.

(8)

The wireless communication apparatus according to any one of (1) to (7),

in which the wireless transmission processing unit intermittentlytransmits the next inter-training signal after a predetermined periodhas elapsed since the inter-training signal had been transmitted.

(9)

The wireless communication apparatus according to any one of (1) to (8),

in which the wireless transmission processing unit transmits theinter-training signal in one of the frequency channels in a case wherethe transmission data is transmitted using a plurality of the frequencychannels.

(10)

A wireless communication method to be performed by a wirelesscommunication apparatus, including:

generating a preamble signal including header information;

generating an inter-training signal including at least part ofinformation of the header information; and

transmitting transmission data after transmitting the preamble signal inat least one or more frequency channels among a plurality of thefrequency channels and transmitting a plurality of the inter-trainingsignals by utilizing one or a plurality of the frequency channels amongthe plurality of the frequency channels during a transmission period ofthe transmission data.

(11)

A program for causing a computer to execute processing including stepsof:

generating a preamble signal including header information;

generating an inter-training signal including at least part ofinformation of the header information; and

transmitting transmission data after transmitting the preamble signal inat least one or more frequency channels among a plurality of thefrequency channels, and transmitting a plurality of the inter-trainingsignals by utilizing one or a plurality of the frequency channels amongthe plurality of the frequency channels during a transmission period ofthe transmission data.

(12)

A wireless communication apparatus including:

an inter-training detecting unit configured to detect an inter-trainingsignal including at least part of information of header informationincluded in a preamble signal from a received signal in one or aplurality of frequency channels among a plurality of the frequencychannels; and

a wireless communication control unit configured to specify usagesituations of the plurality of frequency channels on the basis of thedetected inter-training signal.

(13)

The wireless communication apparatus according to (12),

in which the inter-training signal includes at least one of informationregarding the frequency channels to be utilized for transmission of asignal, information for identifying a wireless network to which atransmission source of a signal belongs, or information regarding atransmission period of a signal.

(14)

The wireless communication apparatus according to (13),

in which the wireless communication control unit specifies the frequencychannels which are available to the wireless communication apparatus onthe basis of information described in the inter-training signal andcontrols transmission of a signal utilizing the specified frequencychannels.

(15)

The wireless communication apparatus according to (13) or (14),

in which the wireless communication control unit determines whethertransmission right of a signal of the wireless communication apparatusis acquired, on the basis of information described in the inter-trainingsignal.

(16)

The wireless communication apparatus according to any one of (13) to(15),

in which the wireless communication control unit sets a period duringwhich transmission of a signal of the wireless communication apparatusis inhibited, on the basis of information described in theinter-training signal.

(17)

The wireless communication apparatus according to any one of (12) to(16),

in which the inter-training signal includes at least one of coding andmodulation scheme information of a signal, transmission powerinformation, receiving sensitivity information, information regarding aspatial reuse technology, or information regarding a wirelesscommunication apparatus of a recipient of a signal.

(18)

The wireless communication apparatus according to any one of (12) to(17), further including:

a transmission power control unit configured to control transmissionpower of a signal of the wireless communication apparatus on the basisof information described in the inter-training signal.

(19)

A wireless communication method to be performed by a wirelesscommunication apparatus, including:

detecting an inter-training signal including at least part ofinformation of header information included in a preamble signal from areceived signal in one or a plurality of frequency channels among aplurality of the frequency channels; and

specifying usage situations of the plurality of the frequency channelson the basis of the detected inter-training signal.

(20)

A program for causing a computer to execute processing including stepsof:

detecting an inter-training signal including at least part ofinformation of header information included in a preamble signal from areceived signal in one or a plurality of frequency channels among aplurality of the frequency channels; and

specifying usage situations of the plurality of the frequency channelson the basis of the detected inter-training signal.

REFERENCE SIGNS LIST

-   11 Wireless communication apparatus-   53 Network managing unit-   54 Transmission frame constructing unit-   55 Wireless communication control unit-   56 Header information generating unit-   57 Preamble generating unit-   58 Inter-training generating unit-   59 Transmission power control unit-   60 Wireless transmission processing unit-   63 Wireless reception processing unit-   65 Inter-training detecting unit-   66 Preamble detecting unit-   67 Header information analyzing unit-   68 Received data constructing unit

The invention claimed is:
 1. A wireless communication apparatuscomprising: a preamble generating circuit configured to generate apreamble signal including header information; an inter-traininggenerating circuit configured to generate an inter-training signalincluding at least part of information of the header information; and awireless transmission processing circuit configured to transmittransmission data after transmitting the preamble signal in at least oneor more frequency channels among a plurality of the frequency channelsand transmit a plurality of the inter-training signals by utilizing oneor a plurality of the frequency channels among the plurality of thefrequency channels during a transmission period of the transmissiondata.
 2. The wireless communication apparatus according to claim 1,wherein the inter-training signal includes a training sequence includedin the preamble signal.
 3. The wireless communication apparatusaccording to claim 1, wherein the inter-training signal includes atleast one of information regarding the frequency channels to be utilizedfor transmission of the transmission data, information for identifying awireless network to which the wireless communication apparatus belongs,or information regarding the transmission period of the transmissiondata.
 4. The wireless communication apparatus according to claim 1,wherein the inter-training signal includes at least one of coding andmodulation scheme information of a signal to be transmitted by thewireless transmission processing unit, transmission power information,receiving sensitivity information, information regarding a spatial reusetechnology, or information regarding a wireless communication apparatusof a recipient of a signal.
 5. The wireless communication apparatusaccording to claim 1, wherein the wireless transmission processingcircuit repeatedly transmits the inter-training signal by utilizing oneof the frequency channels.
 6. The wireless communication apparatusaccording to claim 1, wherein the wireless transmission processingcircuit switches the frequency channel to be utilized for transmissionof the inter-training signal over time.
 7. The wireless communicationapparatus according to claim 1, wherein the wireless transmissionprocessing circuit transmits the inter-training signal beforetransmission of the transmission data or after transmission of thetransmission data in one of the frequency channels.
 8. The wirelesscommunication apparatus according to claim 1, wherein the wirelesstransmission processing circuit intermitently transmits the nextinter-training signal after a predetermined period has elapsed since theinter-training signal had been transmitted.
 9. The wirelesscommunication apparatus according to claim 1, wherein the wirelesstransmission processing circuit transmits the inter-training signal inone of the frequency channels in a case where the transmission data istransmitted using a plurality of the frequency channels.
 10. A wirelesscommunication method to be performed by a wireless communicationapparatus, comprising: generating a preamble signal including headerinformation; generating an inter-training signal including at least partof information of the header information; and transmitting transmissiondata after transmitting the preamble signal in at least one or morefrequency channels among a plurality of the frequency channels andtransmitting a plurality of the inter-training signals by utilizing oneor a plurality of the frequency channels among the plurality of thefrequency channels during a transmission period of the transmissiondata.
 11. A non-transitory computer readable product containing aprogram for causing a computer to execute a method the method:generating a preamble signal including header information; generating aninter-training signal including at least part of information of theheader information; and transmitting transmission data aftertransmitting the preamble signal in at least one or more frequencychannels among a plurality of the frequency channels, and transmitting aplurality of the inter-training signals by utilizing one or a pluralityof the frequency channels among the plurality of the frequency channelsduring a transmission period of the transmission data.
 12. A wirelesscommunication apparatus comprising: an inter-training detecting circuitconfigured to detect an inter-training signal including at least part ofinformation of header information included in a preamble signal from areceived signal in one or a plurality of frequency channels among aplurality of the frequency channels; and a wireless communicationcontrol circuit configured to specify usage situations of the pluralityof frequency channels on a basis of the detected inter-training signal.13. The wireless communication apparatus according to claim 12, whereinthe inter-training signal includes at least one of information regardingthe frequency channels to be utilized for transmission of a signal,information for identifying a wireless network to which a transmissionsource of a signal belongs, or information regarding a transmissionperiod of a signal.
 14. The wireless communication apparatus accordingto claim 13, wherein the wireless communication control circuitspecifies the frequency channels which are available to the wirelesscommunication apparatus on a basis of information described in theinter-training signal and controls transmission of a signal utilizingthe specified frequency channels.
 15. The wireless communicationapparatus according to claim 13, wherein the wireless communicationcontrol circuit determines whether transmission right of a signal of thewireless communication apparatus is acquired, on a basis of informationdescribed in the inter-training signal.
 16. The wireless communicationapparatus according to claim 13, wherein the wireless communicationcontrol circuit sets a period during which transmission of a signal ofthe wireless communication apparatus is inhibited on, a basis ofinformation described in the inter-training signal.
 17. The wirelesscommunication apparatus according to claim 12, wherein theinter-training signal includes at least one of coding and modulationscheme information of a signal, transmission power information,receiving sensitivity information, information regarding a spatial reusetechnology, or information regarding a wireless communication apparatusof a recipient of a signal.
 18. The wireless communication apparatusaccording to claim 12, further comprising: a transmission power controlcircuit configured to control transmission power of a signal of thewireless communication apparatus on a basis of information described inthe inter-training signal.
 19. A wireless communication method to beperformed by a wireless communication apparatus, comprising: detectingan inter-training signal including at least part of information ofheader information included in a preamble signal from a received signalin one or a plurality of frequency channels among a plurality of thefrequency channels; and specifying usage situations of the plurality ofthe frequency channels on a basis of the detected inter-training signal.20. A non-transitory computer readable product containing a program forcausing a computer to execute a method, the method comprising: detectingan inter-training signal including at least part of information ofheader information included in a preamble signal from a received signalin one or a plurality of frequency channels among a plurality of thefrequency channels; and specifying usage situations of the plurality ofthe frequency channels on a basis of the detected inter-training signal.